Refusal to issue paid up letter

I am so tired of Telkom's pathetic service. I took a contract phone and lost it 8months into the contract, I kept paying the account till I received a call in August to upgrade since the contract had come to an end, I declined the offer as I recently bought my iphone15 cash recently through Telkom. I have visited Telkom's branches as I found out that the lady did not cancel contract as requested on the call for upgrade, I was billed for services I did not use and received no notification from Telkom to advise accordingly. I have called, loggen numerous incidents and requested a paid up latter, to no satisfaction, I have received a call to say case was resolved, but no paid up letter issued. I am so frustrated as this is affecting my second bond's approval! I need my paid up letter! I have paid more than what is due!!