terrible customer service & incompetence

We sent through a change of ownership request where I was going to take over my brother in laws decoder as he had two. The forms were completed and sent through on the 23rd of October 2018 along with our I.Ds as requested. On the 1st of November my brother in law was debited for both decoders so we assumed that ownership hadn't changed yet. I then started receiving phone calls from the 5th of November from DSTV stating that I owe R920 for the one decoder and I explained numerous times that this decoder was already paid for as they double debited the previous owner. We then asked for the consultants to allocate the funds to the decoder that was changed to my name and they would respond and say that the request has been sent through however few days later I would get another call from a different consultant saying I owe R920 again!!! This has been very frustrating as a simple request of allocation of funds has not been done and it has been a whole month now. I had to resort to paying a total amount of R1880 as now my balance includes November and December and up until now the funds that were double debited have not been allocated. I need someone to sort this out asap and should this affect my credit profile, I shall take legal action.