PAYING FOR NETSTARS MISTAKES

What disgusting service from Netstar, i had two cars, both ensured by Dial Direct, i sold the one car and notified Netstar, they took it upon themselves to delink both devices and have been charging me ever since. Now i get an increase letter and i query why are there two devices on the letter when i only got one. When i called to cancel you DID NOT say there is a cancellation fee and instead have just been charging me for both devices. Now you want to make me pay a cancellation fee and do not want to factor in the mistake that you made and are making me pay for as i should not have been charged for the second device and it SHOULD NOT have been delinked. I will take legal action against Netstar and unless you can prove i phoned in and asked you to delink both devices, you will pay my legal fees as well as i did not at any point say so. Furthermore, i have been querying why the amount is so much and you have not been responding to me, why am i as a consumer paying for your mistakes? Who made the mistake and why did you not charge me the cancellation fee back then? Rightfully i should not have paid for a device since it was cancelled. SORT OUT YOUR MISTAKES AND CUSTOMERS SHOULD NOT HAVE TO PAY FOR YOUR MISTAKES!!!! I want all my money back!