MRP Mobile take illigal money via debit order from my bank

Hi I have cancell my contract with MRP mobile in June 2015, but they still try to deduct service fees from my bank via debit order. Everytime I must go t bank to reverse money and block them, but then they just use other code the next month, I tried over years to phone and send emails that I don, t have a contract anymore, I don, have the phone either and dont use their services for 2 years no more, but they ignore, they dont answer their toll free number, and agsin deduct money in Des, Jan and Feb, everytime it costs me money to reverse and now my bank say it could have bad credit on my name if I keep reversing the debit orders, what can I do because they dont want to stop the debit order on their side,,, Help can I make a legal case as is this not ******* to still try to get money from my bank account without my permission