Vehicle is sold - cancel subscription!

I had a monthly service through my insurance with Netstar. The vehicle was sold, and Netstar and my insurer was made aware of this. my understanding was that my insurer would have advised Netstar of the vehicle being sold. I guess not! I am still receiving statements, when i email and call Netstar no one is able to assist me. Netstar stop communicating with me, i am no longer using your services as the vehicle is sold, also i don't own you anything. Can someone please ensure that this matter is closed, now...