How do I recover a debt in Spain?

Having hired a car from an airport in Spain. I used all of the fuel returning it empty, as per the hire contract. However two weeks later I received a letter back in England from the hire company stating there was Water in the fuel tank, that the tank had to be cleaned and that they had taken 210 euros from my credit card to cover the cost! I am shocked as this had nothing to do with me. All I did was drive the car and didn't ever add any fuel. I have sent several emails to the hire company pleading my innocence and asking for the money to be returned to my account. They seem to be ignoring me!

My question is: How do I go about seeking legal representation and is there such thing as a small claims court in Spain who will take on the recovery for me?

Dear Sir,

For 210€ I would really forget the matter. You are going to spend much more money seeking a refund. Report the case to the Police.