Poor Customer care-Incorrect Billing

I have been a DSTV Multichoice customer for many years. I was contacted to change over from DSTV Premium to Price Lock in June and the new Decoder was installed on 2 July. To my dismay my bank account was debited on the 1st August, with almost three times the amount I was supposed to pay according to the Price Lock sales lady. I have since spoken to Customer Care,Price Lock and e-mailed to no avail. As a customer you cannot directly speak to the Accounts Department, but the call center staff can only escalate and you receive no response. This service is really poor and needs to be addressed most urgently. I am cancelling my debit order as I have lost faith in Multichoice.