Edgars nigtmare

I had an account with Edgars in June 2019. It was in arrears and handed over. I went to the store Northgate Mall they say I can pay at the store. I paid it up in full. Recently did my credit check it appears I'm still owing them the same amount. Went to Edgars store to enquire, they asked for my I.d. They checked on their system they said I don't have a account with them, then they called head office they also say I don't have an account with them. I told them I used to and I paid it up I need a settlement letter. And they said they can't help me as it appears on their system I don't have an account with them. I joined Transunion thinking they could help me, they said they need a settlement letter to be able to help me. I don't know what to do now