Bad Service

I received an sms from Telkom Mobile that my account was overdue. On investigation I found that they debit my account on the 24th and my contract clearly states that I get paid on the 25th. I called the call centre and they said I must go to the bank and pay it manually. I told them no they can debit it cause it is a problem from their side. The lady said thats all they can do otherwise they can debit me double next period but my line will be suspended till then. I told the lady they cannot suspend my line because the fault is lying with them they are in breach of contract not me but she insisted thats all i can do.