No answers from Mixed Telematics

Mixed Telematics keep on sending me emails and messages to say my account is unpaid. I cancelled this policy already in May. All the correspondence has been send to them several times. I even post on Hallo Peter. Someone called me just after that. I couldn't take the call because I was busy on another call. I called the number immediately after that. I just got a message that the number is wrong. Please stop harrassing me about a policy which I cancelled well in time. If this is not stopped now, I will seek legal action from my side.