They re-instated my paid up and closed account without informing me

My account was paid up and closed early in 2019. I even have the letter that confirms that my account was paid up and closed. Edgars has been sending me statements on a monthly basis since from mid-2020 saying that I am owing them. I have called, emailed, and did anything possible to to prove to them that my account was paid up and closed but they still accumulate the interests every month that negetively affect my credit record. I need assistance with this asap.