Wonga is a dubious company out infringing consumer rights

I v never received such bad service from a highly inconsiderate company. I took out a 3 months loan and my last installment was supposed to go off on the 31st of December. I called their call centre and even sent them an email that they cannot debit my account on the 15th of December as I will only get my money on the last day of the month. They never rep**** but went ahead to debit my account and was not successful on the 15th. On the 17th at 6am they sent me an sms that my account has been handed over to their attorneys and I should contact their attorneys. What madness is this because I have not breached the contract I signed. I v never signed for the 15th. Can someone help me who is a lawyer with such consumer right infringement I'm getting from these vultures. I have the email I sent and the sms they just sent me now