Cancel the car insurance, the car is no longer in my possession

I've had car insurance with them for a couple of months, now I am trading in the vehicle to get another one. Their cancelations team is always unavailable, they don't even have a direct number. Very *****, their service is bad, I spoke to a lady yesterday to try and insur the new car and remove the old one. She was rude and just annoyed. Decided to go to another company, now it's a hustle to cancel.