Paid up letter

I have an contract with Cell C that I recently paid off on the 21/07/2025. I have emailed them proof of payment and requested for a paid up letter. I even called customer service and they passed me to contract department which two 2 cases for me without any resolution. It is also a train smash to be escalated to a manager.. Like why is it so difficult to get a paid up letter while I was promised that I get it after 2 working days.