Debit order more than 20 times the monthly charge and no further feedback?!?!

I have a pricelock contract with Multichoice. I received a sms from my bank that they tried to put through a debit order in excess of R20****! Once Ive phoned to try and resolved I was told that I was only partially invoiced monthly and that this was now due. Ive checked statements regularly and NEVER have there appeared an outstanding amount. Furthermore, Im trying to resolve this from my side but I keep on being told that somebody from either Finance/Pricelock/Customer care will phone me back within 48 hours. Ive now logged a request 4 times already with no such calls!! I am desperate to have this resolved before month end but clearly if you have a monopoly you dont care about your customers