Cartrack worst service ever

i have never in my life worked with people that dont understand you i Have been trying to cancel my cartrack tracking device for i dont know how long Everyday they phone and say that i have an outstanding amount to pay but i never agreed to pay a year in advance - which we always do they just accept that you would like to do it again. Now im registered as a bad payer cause they dont listen Im sorry but i will never recommend anyone to use cartrack I would just like to not have a tracking device with them anymore and i would like to sort out this account

I have sent email after email after email

Im still waiting for the lady to phone me back regarding this matter its been more that a month now

Any advice as im so tired of calls from cartrack accounts department