Cell C conract turning into a ****

I had 2 cell c contracts , the other contract I never received the SIM card. Decided to settle n close both contracts , 21 April 2023 I settled them both but to my surprise I still get debited , I tried many times to call every time they say we apologize it's a mistake on out side we will fix it , however the mistake is never fixed , I have to dispute the debit every month and it is affecting my credit score .