Payment allocation and cancellation of contract

I have settled my account in November 2021, but used an incorrect reference number. I have forwarded proof of payment via email to various Cell C addresses for allocation and contact cancellation, for 2 months nothing has been done. I have been calling customer service and I have been given different stories by their customer service agents (that they have backlog, case has been closed, that i have to wait util the relevant dept. assist). Cell C keeps on debiting my account on a monthly basis. DON'T KNOW WHAT TO DO ANYMORE, BECAUSE NO ONE IS WILLING TO ASSIST AT CELL C.