They should be reported

My account was paid up in October, to date i am still getting emails demanding payment. i have sent proof of payment, i have received a paid up letter and still they are sending emails demanding payment. When i call in, the consultant drops the call. We have been fighting with HTN for the last 2 months. Yesterday again i sent a proof of payment and a paid up letter. Lo and behold, this morning i get another email demanding payment. Never before have i come across such *********** staff, neither able to read or write.