Worst experience!!

I was under Debt Review since January 2020,My Discovery Credit card was flagged and included in the review.Originally the Account was via FNB bank since discovery didn't have there own Bank.When they became their own bank they migrated the Account.I have a Paid up letter from FNB stated the account is closed and paid up,i've been getting calls and messages everyday for the past 9 months saying i owe them money,Prior to this i received nothing,My debt review was finished in March and Clearance certificate issued.Yet i still get calls and it still shows on my credit profile affecting my score.Your call center agents and email support cannot seem to understand what is going on.Discovery and FNB need to contact each other and sort this out.