Account was settled with the store why call me when I have provided you with proof that I have paid the account.

I had an account with Tenacity which I settled with Tenacity as they were offering me a discount, I settled the account received a settlement letter from them and when I received a call from Vertex Solution who informed me that my account was handed over by Tenacity, I explained to them that I have settled the account and shared the settlement letter with them 5 times, but to my very annoyed and surprise I still get calls and the amount is increasing as the consultants are saying I am charged for calls, SMSs and e-mails send. WHY CALL ME? when I have informed you numeral times that I have settled the account 2 years ago. Please sort your issues with Tenacity as they were not suppose to accept my settlement money and redirect me to Vertex Solutions to pay.