Cannot get rid of Cell C

I cancelled my contract with Cell C earlier in 2018, when it ran out and I did not wish to renew it. Because my cancellation was not processed timorously and I was continuously billed I had to pay R1000 by 31 May 2018 as full and final settlement. The amount was deducted from my Capitec account on 25 May 2018 after I was handed over to Cell C's attorneys, Hammond Pole. I informed Hammond Pole on the deduction and asked them to confirm that the account is now fully paid up and closed. Confirmation was received. I am however still continuously billed although I do not use the account at all. All me please to Cell C leads to nothing and they want me to pay yet again before my account is closed.