Years old billing surprise

If I could I would rate with -1 star. 3 years ago I canceled my account back then already I had back and fro arguments about billing as they charged me for services after cancellation. Today I get a call to say I have been handed over because there is a cancellation fee that is outstanding. Why are they try after 3 years to ****** money from me…. How do they run a business???? Please fix this mess