No paid up letter after dillagently paying the account - waiting forever!!

This will be going on the second week waiting for my paid up letter from FNB, I received a complaint reference number:***NF. I call FNB and they refer me to complaints department and then it goes to the premier bankers people who cannot help me. so then I emailed the following emails: *** AND *** and no response received, they called me once and I missed the call just ONCE and they never called again, why do other creditors give the paid up letters within a day and FNB is taking FOREVER???? Please you say you offer a service so where is it????