Pathetic service

I switched banks from fnb to discovery bank , soo I emailed debt rescue on the 8th of july 2022 to request that they changed it I even send through the bank confirmation letter , but no response when I call in to speak to their customer service it just rings , I have sent through another two emails but no response today it is the 12th of september now im just getting threat emails that I did not pay etc.... but how is this my problem I have been under debt review for more than 4 years never missed a payment