Debited on wrong date, will not pay bank penalty

Telkom Mobile debited my account on the 24th of July although the agreed date IS THE 25TH . I did not get an sms or an email to warn me of the debit going off on the 24th of July. I was charged R115 for a returned debit order by my bank . I called their customer care line on Monday Morning. I was given a case number and told I will be called back with feedback within 72 hours. 72 hours have passed and I got no response. When I called again this morning I was told that the query was still in the queue and has not yet been assigned to an agent (pathetic ) I was told the manager will call me back in 2 hours to resolve the matter , still no response. This is unacceptable service as I did not break the contract and should not be liable for the charges. Waiting for a response. and my money back as they debited my account today .