Billing incompetence

My experience with this company has been absolutely terrible. After a year I was finally allowed to cancel my contract which I did be contacting them a month before the end of my contract and confirming that I am cancelling, as well as the date if my last payment and asked that they confirm that everything is in order. I received a confirmation letter stating that the last payment is correct and that everything is fine and that I will no longer be debited. Yet a month later they again debited my account. I sent a mail forwarding their confirmation and asking for the issue to be resolved, which was ignored. Now I am getting regular threatening emails about my outstanding account. I have sent multiple emails but they seem completely unwilling to look into the matter, or so totally *********** that they are unable to. I wish nothing more than to be completely rid of this ridiculous company! Stay away as far as possible. There are many wonderful ISPs around. Avoid this company.