Unable to cancel and get my money back

Terrible service from this company and would not recommend to anyone. I cancelled my account when I sold my vehicle. The company has refused to acknowledge cancellation of my account and keeps transferring my calls then dropping them. They continued to bill me a decreased amount that is just low enough to not show up on sms notifications and when I enquire they are unable to tell me why I am still being billed. The one helpful person I spoke to said that the company would credit the amount I have been paying for the past year and a half. Now no one knows why the credit is not being approved and my account is still open despite it having been cancelled multiple times.