HORRIBLE SERVICE FROM MTN SA

Good Day I have a problem with MTN, I am paying for the phone I returned in JULY and I cant seem to cancel my contract as it was now overdue. The guy who was helping me was Terry Morake when I first bought A30 Samsung phone. I specifically told him that I need a dual sim cad phone and he said he will check and never got back to me. Instead the process continued and I thought the phone was dual sim but when I received it, it was not. So I returned the phone within 5 days at MTN Store in Forest Hill Mall (their reference number is IRMS305440). They said I must call MTN to notify them so that they can be able to collect the phone and I was given this reference number : Ref : *** after so many calls. Ever since then I have been calling MTN but I cant seem to get the right answer as to what is happening with the cancellation of the contract phone but the debit order is going through every month. So I decided that I will return the debit order until I get an answer. One of the consultants told me that the process is long but no valid explanation and why am I being debited for the phone I don't have. I need answers and I need this to be cancelled. Currently I am receiving a lot of different numbers from MTN which doesn't make sense or give me a valid information : ***, ***,*** etc the last one was *** on Sunday the 25th October 2020