poor client service

Tgf group handed my account offer to harm and pole some debt collectors I requested a settlement letter it was provided .I paid my account in full on the 21/02/2019 and 3 months dowb the line its advise that I am still listed with the credit beru I than requested a paid up letter to provide transunion I called again and they advised that tgf or the debt collectors send them feedback that my account is not paid in full .I have reported tgf group on hello Peter and no feedback yet .I am really not sure what to do anymore .I have a proof of payment ,I have a settlement letter and I also have a paid up letter so I'm really not sure why and how I still owe them .