Horrible service

Horrible service .. when i owed the account, they would call every hour ,so i decided to pay it off after they gave me the settlement amount. I payed on the 02 feb 2021 and i sent my proof of payment and now i want my payed up letter they sending me pillar to pillar . I was told to call nimble group and they telling me to call jet and they never answer their emails . Where did my money go ??! When I passed by one their stores yesterday to my surprise my account is still in arrears. *** ?? Can i have my payed up letter.