Could I get some help?

I bought a domain name, a long while ago from an EXTREMELY Shady domain provider.

I emailed, then called, then confirmed. multiple times. I have a CONFIRMED cancellation email that I did not want to renew the domain and cancelled the account.. YET

They continue to send me "Upcoming Payment Notices" NOW, unbelievably I have an email with a subject line "Overdue Balance - Account Pending Collections" ... and here's the best part: The email opens as "Your service has been suspended due to a previously declined payment..." "..with a total overdue balance of $15.17. If the balance remains unpaid, the debt will be forwarded to a collection agency incurring a fee of $18.95 in addition to the overdue balance".

W T F?! I have a CONFIRMED ACCOUNT CANCELLATION EMAIL. AND ITS A F&&&& Domain.

What do I do? I already called, emailed, multiple times. I really want to tell you all which domain provider this is .. they're big.