A mother whose son was severely injured by his birth parents is calling for tougher sentences for child cruelty following two high profile cases in Kent this year.Jody Simpson and Tony Smith were sentenced to 10 years after injuring their baby so badly that his legs had to be amputated.Last week parents from Tonbridge were given 8 years for cruelty to their 19-day-old son, but campaigners say the sentences don't go far enough.