Billed without notice!

I bought my 1st car in Aug 2012, the insurance company organised the tracker unit stated it was included within the premium. My insurance was cancelled in June 2014. I called Altech netstar to find out if they would be removing the unit or if i could pay the fees, they told me the account is up to date and that i will be contacted. I was never contacted. I tried calling in to test the unit to no avail. My car was written off in Feb 2015 and they are still sending me invoices till current. I contacted them via phone (March 15) and asked for a signed contract that i acknowledged I should pay this and the procedures. I was emailed a two page document with no date or signature and told it was handed to the legal dept. Today i get a call from credit works saying that I'm being reported to the credit bureau. This is the worst customer service I've ever experienced. I was never called or mailed stating that I am now responsible for this account. I even agreed to pay the outstanding until the car was written off with the agent on the phone and asked for a revised statement. I just received statements which i queried! And now I'm getting rude phone calls from a debt collector