Weekly Returned debits and incorrect billing

I upgraded my contract with Telkim mobile in October and was advised that my new instalment would be now R399.00. I was not told of any additional fees that I was supposed to pay and to my surprise, my account was not even debited on my pay day (20 Oct 2015) but I still left R400 in my acc. I then got an sms stating that I would get debited with the amount of 1200 and odd rands on the last day of October. In shock, I called Telkom mobile, I was told about fees that I was initially not informed about and was advised that a collections consultant would call me to make arrangements and that person did not call. Telkom mobile has been attempting to debit my account WEEKLY since then with an amount of R 949 (I don't get paid weekly and I don't know what that amount is for) and this is ruining my credit score. Whenever I call, no one seems to know how to assist me, they make promises just to get me off the phone. And today, when Kamogelo could no longer answer my questions, he decided to place me on mute... if that's how you deal with your customers (irrate or not), I am more than willing to give the phone back and cut all ties with Telkom mobile.