Faulty deductions on bank account.

After the account was paid from my airtime, eVod still tried to deduct money from my bank account. I've send them an email about the problem. They sort it for me in Jan, but still they kept on deducting money from my bank account. They don't want to pay the deduction fee's on my bank account and be liable for their faulty sistem. Is it my problem they can't manage their own sistem? Isn't is why there is an accounts department to monitor such faults on the sistem?