Unfair treatment

Hi, I had an account with Truworths and it was handed over to ARA Debt collectors of which I've made sure that it was paidup in December 2020 & demanded paidup letter. To my surprise on April 2022 I've received call from DMC debt collectors with the same account and I've forwarded paidup letter to them of which never got any updates. Until today called by Lazola from DMC again with the same account.

Kindly advise in this matter