Bad customer service by Markham

I had bad experience with this credit provider, I have settled the account I had with them in July 2019. I requested them to close the account and send me the paid up letter since then I never receive the letter. April 2021 I wanted to purchase a vehicle and only to find out when I check my credit report the account was never closed as a results it's in arrears since August 2019 and now I have to wait because of their stupid mistake and bad communication with their customers. They never phone/call me to inform about this stupid mistake and now I have to wait until when I don't know. Can someone assist me because I cannot wait for the 3 months clearance. I never receive such bad customer service and I wouldn't recommend either to one of friends or family to this bad service provider