Account Billing Concern

I'm so disappointed in the service from this service provider. My one vehicle was written off and tracking unit was reinstalled in my new vehicle and after missing one months payment I asked for a invoice so I can make a payment only to discover I was still being billed on a vehicle for services that is not my vehicle anymore and further to this for 14 months without knowing it, shocking to realize some things happen for reasons as if I never found it out this way come time to claim for something I would have been told but the registrations do no match etc. Still waiting after numerous promises I will have feedback and to date nothing. However called daily for the outstanding amount. Really considering leaving service provider.