Requested to Pay for a Policy I have Cancelled and Threatening Me

I have tried contacting Telematics in a numerous times but they just keep me holding for long as I wanted to cancel the policy, also sent some emails to them for cancellation but no one was responding from their side.

I ended up reversing the amounts from my account so that I can get their attention and I asked them to close my policy and now I am getting some invoice for me to pay for over 4 months worth of premiums, so I don't know what is it for and I have asked for a breakdown but still no assistance.

Is this how you guys conduct your business with threats?