Requested for a paid up letter over 2 months ago and cell c has still not allocated the payment to the correct account and sick and tired of sending proof of payment do your damn job cell c or go out of business

My account was paid in full in August and it is now the 1st of November and payment has not been allocated to My account as per cell c I have called numerous times and sent proof of payment over 6 times and they are so *********** that they can't do their job correctly and my credit score has gone down due to their failure to do their jobs and i am tired of contacting them and they keep saying the same thing like a broken record and they dont even do anything to make their services better i think they should go out of business