Drivers have been forced to pay out more than half a million pounds over the last three years - simply because some parking machines do not give change.

Between 2015 and 2017 local authorities in Kent have kept £530,488.76 in money which could have been returned to drivers.

But the true figure could be much more than that, as only six of the 13 councils asked gave figures on the amount collected.

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As the average price of a new small car last year was £12,715 this means you could have bought 41 vehicles for the same price.

The worst culprit was Medway Council, which collected more than half the total amount over the three years, to the tune of £283,172.13.

Now motoring organisation the RAC is calling for a change.

Spokesman Rod Dennis said: "I think drivers would be shocked by the amount councils appear to be making simply by parking machines being out of date.

"If we're seeing six-figure sums it's pretty shocking.

"It really is something that needs to change and fast.

"There doesn't appear to be any defence for it apart from the fact some of these machines are very old.

"In the days of contactless cards we really don't see why this sort of technology shouldn't be put in place in council-run car parks.

"We have to be honest - there's a cost attached to these.

"We know how under the cosh financially many councils are but we believe it's imperative on them to publish plans for drivers and visitors to these particular regions in Kent to explain when they can expect these kinds of machines to be upgraded.

"It's not really acceptable that machines don't issue change.

"What we would say is councils need to be clear about what they're doing with this money.

"We're talking about six-figure sums every year that people are simply putting in machines and not getting any benefit from.

"We think it really is up to councils to publish details on when they plan to update these machines."

"What we would say is councils need to be clear about what they're doing with this money" - Rod Dennis

All councils apart from Thanet District Council responded, but figures were released for just six of the authorities, meaning the true cost could be much higher.

After Medway the authority with the highest income from overpayments at parking machines was Tonbridge and Malling Borough Council, which collected £98,000.

Gravesham Borough Council benefited from £94,630.05.

This is followed by Shepway District Council which recovered £52,657.95 in 2015, 2016 and 2017, Swale Borough Council collected £1,192.59 and Maidstone Borough Council £836.04.

The number of machines operated by each council varies, but some councils have revealed they have added more each year, including Swale Borough Council and Maidstone Borough Council.

There are many different ways you can pay to park in the town centre.

Some councils in Kent have recently been driving visitors and residents to ditch cash in favour of mobile payments.

One of the those is to use mobile apps which allow you to pay the exact amount for your tariff without having to look for change.

But convenience comes with a price as some apps slap a surcharge on top of what you pay for the ticket.

Head of highways maintenance and parking at Medway Council, Simon Swift, defended the measures by saying the surplus cash is ploughed back into the upkeep of the roads.

“Our pay and display parking charges are amongst the cheapest in the county,” he said.

“The fees are clearly advertised in our car parks, and on our website, and states the machines do not give change.

“This is standard practice in car parks across the UK.

“Motorists can also pay to park by phone and online through RingGo in all council owned car parks and streets which require pay and display parking.

“The popular alternative enables motorists to pay the precise parking fee by credit or debit card.

“The money is used for highways improvements.”

The car park which took the most money last year in Medway was Blue Boar Lane in Rochester, where £4,800.10 was collected in 2017 alone.

In the two years before it was Littlewoods car park in Gillingham, where the most was made in overpayments.

Some £4,953.90 was overpaid in 2016, and £5,047.15 in 2015.

You could purchase 103 season train tickets from Ashford International to London stations for near enough the same price as the amount collected over three years.

Robert Styles, director of street scene leisure and technical services at Tonbridge and Malling Borough Council, said: “This council operates a number of outdoor surface car parks as well as on-street pay and display parking.

“It is the norm pay & display parking machines do not give change and motorists are encouraged to have the correct change available.

“To offer change would require the machines to be bigger and hold significant levels of change to ensure they could continue to work.

“This would increase the risk of them being damaged and targeted by criminals.

“The overpayments are included within the general parking income account and used to support the parking service as a whole.

“This includes the payment of business rates, CCTV coverage, repairs and maintenance, improvements, enforcement, and parking action plans.

“The council offers customers the facility to pay by phone using the Parkmobile system.

“Approximately 12% of drivers currently choose to pay by phone rather than use coins and this is growing year on year.”

A spokesman for Gravesham Borough Council said: “As is common across the UK, Gravesham Borough Council’s pay and display machines do not issue change and this is made clear to the user on all tariff boards within our parking areas.

“The reason this is common practice is because if change were to be made available, money would need to constantly kept within the machines which creates additional security risks, increases the likelihood of faults with the machines and also increases the cost of operating and managing the parking areas.

“To give our customers that do not have the correct change an option to purchase a ticket without overpaying, the council encourages the use of its pay by mobile app service, which is provided by Parkmobile.

“This cashless service was introduced in 2012 and information on the Pay by Phone system is available on our website and on signs located within our pay and display car parks.

“Any income generated from pay and display parking on the public highway is ring-fenced and used to fund the parking service.

“Once all costs of the service have been deducted from the income received, any surplus can only be spent on highway/transport related projects.

“Income generated within council owned car parks is not ring-fenced and forms part of the councils general fund.”

Chief executive of the Kent Invicta Chamber of Commerce, Jo James, said the policy can be frustrating but does not necessarily have an impact on the high street.

She said: “It’s not fair, if there’s a certain charge that’s all you expect to pay.

“I can understand doing it once in a car park but you wouldn’t need that every time as shoppers need to ensure you have enough money for the machine.

“It’s very annoying there’s no getting away from it but you wouldn’t not shop.”