Price lock costs me R3740 and DSTV cant give an explanation

Multichoice offered me Pricelock for R638 a month for two years. They also asked to add an extraview decoder for a total of 749 rand per month. I agreed to their terms and I have been paying R749 per month since around July last year. Two decoders were installed (Main and extraview) In February of this year (2022) they debited R818 from my account. I made a query and they failed to explain why they breached the pricelock contract. On Sunday 27th of February they deactivated my main decoder and left the extraview decoder active. I called them and notified them of their mistake. They reconnected the main decoder and disconnected the extraview as per my request during the phone call. To my surprise I found a balance R3740 on my app payable by me. I called them and they failed to explain the amount of R3740. I have never requested a cancellation of the pricelock and the decoder is still active even on my app. It worries me that they charge me R3740 but they cannot explain it when I query about it. This is **************** and no DSTV package costs R3740. PS. My account is paid in full and up to date. I am being ****** in broad daylight