I am extremely frustrated

I am extremely frustrated. I settled my Woolworths account, reference number ***, eleven years ago. Despite this, I continue to be harassed for payment. I have sent numerous paid-up letters, yet the more I assert that the account is settled, the more messages and phone calls I receive demanding payment. Some representatives have even been rude to me. Nimble needs to resolve this issue. I intend to file a formal complaint with the National Credit Regulator (NCR), Financial Sector Conduct Authority (FSCA), and National Consumer Commission (NCC). I request that you escalate this matter and remove me from your call list immediately.