outstanding billing after cancellation

Netstar vehicle tracking -admin is so disorganised, My account was cancelled after using netstar for over 8 years with no issues ever with payment. i cancelled services as i no longer required it. I was then offered a discount of 30% per month which i declined. However after cancellation, I am been told over a year later that I still need to pay, as no cancellation received. This is absurb in my opion, i feel it is a way to extract money from customers from portraying to be disorganised. <br> <br> Really frustrated.<br> <br>