Cancelled faulty landline yet still billing me

I cancelled my landline last year September, due to a constant battle as it was hardly working.<br> Since then I have received numerous invoices for payment.<br> Each month seems to have a different amount one amount less than the previous month. This has been an incredibly frustrating service to pay for and cancelling such service has offered me no relief but instead a tremendous amount of frustration. To top this all off I received notifications from the credit bureau that I now have a late payment listed on my itc score.<br> <br> I have emailed these forms off twice now and really have no where left to turn.<br>