Frustrated client

I was insured with King Price insurance. Unfortunately i had to trade in my vehicle, therefore i no longer needed the insurance. It has been such a hassle to get them to cancel my cover. My account is still getting debited every month and i cant cancel. I have sent emails and called their office to no avail. All i get are autogenerated responses on my emails and im put on hold for long periods without speaking to any consultant. When we are looking for cover they are very quick to respond but when we want to cancel, they are nowhere to be found.