Drivers were mistakenly handed Dartford Crossing fines totalling more than £4 million in 12 months, an investigation has found.

National Highways cancelled 59,007 penalty charge notices (PCNs) in the year after it switched to a new provider to manage payments for the south-east England crossing, Freedom of Information figures obtained by the PA news agency show.

That is compared with 3,595 during the previous 12 months.

The total value of the 59,007 PCNs at the point of issue was £4.1 million, as each was £70, reduced to £35 if paid within 14 days.

It's taken an awful lot of my time and wasted a lot of my energy

The Dartford Crossing consists of a bridge and two tunnels, which connect Thurrock in Essex with Dartford in Kent.

Private company Conduent was handed a £150 million contract by National Highways to manage crossing payments from July 28 last year.

After Conduent began its work, there were instances of drivers being fined or charged when a vehicle with a similar plate to their own used the crossing, and being unable to make payments and manage accounts.

National Highways said it has “resolved the issues”.

Crossings made between 6am and 10pm are chargeable, with prices for one-off payments ranging from £2.50 for cars to £6 for lorries.

Fees – known as the Dart Charge – must be paid by midnight the day after the crossing, with several available methods such as online accounts, telephone and post.

PCNs are issued when no payment is made for vehicles detected by automatic number plate recognition (ANPR) cameras on the crossing.

Dr Jenny Dunne, 64, was charged 34 times through her Dart Charge account in the seven months to late April for crossings she did not make.

This was partly because a car with a number plate similar to hers – it had a 3 instead of a 1 – was being incorrectly identified by the cameras.

Dr Dunne, from north London, repeatedly telephoned the Dart Charge contact centre but struggled to resolve the situation.

She said: “I had no idea what was happening. At the beginning I got quite upset. I thought my number plate had been cloned so I contacted the police. It turned out the cameras were faulty.

“It’s taken an awful lot of my time and wasted a lot of my energy. I rang them so many times.

“I never felt like they were treating it urgently even though it was happening so frequently.

“They’re very unforgiving if you make a mistake, but they don’t care if they make a mistake. They’ve never properly apologised.”

A spokesman for National Highways said it has apologised to Dr Dunne since becoming aware this article was being written.

Another driver, Sarah Rodwell-Dodsworth, 37, from Ipswich, Suffolk, said she was fined twice in January because the payment card registered with her Dart Charge account to automatically pay for crossings was “removed”.

We were trying to be law-abiding citizens paying the toll as required, and were punished off the back of that

Crossing users were required to re-validate payment cards when Conduent took on its new role, but Mrs Rodwell-Dodsworth said she was unaware of this.

She said: “We had an account set up, there was no reason for the card to be removed.

“It’s quite frustrating. I’ve never had a fine (for the Dartford Crossing) until this occasion.

“In our opinion, we were trying to be law-abiding citizens paying the toll as required, and were punished off the back of that.

“It almost feels like they want to catch you out.”

Each year more than 55 million journeys are made on the crossing, and around two million PCNs are issued for non-payment.

National Highways said in a statement: “There were technical issues with the transition to the new service providers, which resulted in an increased number of PCNs issued and an increase in cancelled PCNs.

“We regret that some customers have experienced issues when making payments and managing their accounts following the transition to the new Dart Charge service providers.

“We understand that anything associated with finances can be stressful, and we apologise for the inconvenience that these customers have faced.

“In the minority of circumstances where PCNs are issued in error, the charge will be cancelled as soon as a customer contacts us to let us know.”

It added: “We have resolved the issues and seen the errors reduce to less than 1% of all PCNs issued.”

Conduent declined to comment.