CELL C IS REFUSING TO GIVE ME MY PAID UP LETTER FOR A PAID UP ACCOUNT 6 MONTHS AGO. CELL C IS A DISGRACE DON'T EVER DO BUSINESS WITH THEM

I'm fed up with Cell C i have been asking for my paid up letter without any help i phoned their useless call center but they said they will help me after waiting for their call back for more than 3 days i called them again someone said i must write a letter to their customers care i did and i have been getting automated emails replies from then without getting any help i ended my contract before time because of this poor customer service and arrogance i was getting from them i paid up my account in March but still now i have not been updated this thing it's even affecting my Credit score because it says i don't pay i have a proof of payment i even emailed it the time after payment they ended my contract by didn't update my account please give me my paid up letter before i can take further action