Debit Order Unsuccessful

My father purchased a cell phone as a gift for me on the 21st May 2015. He asked that his acc be debited on a monthly basis on the 27th instead a debit goes off on the 26th and shows that it has been unsuccessful yet there was sufficient money in his acc also breaching contract where as date is concerned then finding out afterwards that this should have been explained to him. I've received sms's saying my acc is in arrears for 430 days yet I don't even have this phone for 60 days. Been to the store twice and called customer care yet no one could resolve this. Seriously pathetic!!!! Very annoyed. Please advise on who to contact as to this matter. Feel like cancelling this contract and changing back to MTN