Bad service after being a customer for 4 years.

I have been a customer of Cartrack from 2018. +- 4 Months ago Cartrack contacted me as they are receiving false signals from my device and would like to send a technician to repair the device at a cost as my contract has come to an end. I was then offered a maintenance plan at R30 a month extra that would cover all maintenance issues on the device. I accepted the offer and had been paying this fee. I was then called to arrange for a technician to be sent to me I explained my vehicle is in for repairs and could not be done they gave me a off the road letter once car was repaired I called and they cancelled the off the road letter and arranged for a technician to come and repair the device. The technician never arrived without calling me to cancel. Two weeks later I get a call again requesting a technician to come out and repair the device I explained to the lady that the Technician did not arrive the last time and did not even inform me that he/She would not be able to make it. The lady apologised and arranged for a technician to come out to me on Friday 26 August 2022 to repair the unit I just received a call now from the office to inform me that the technician wont be able to make it tomorrow. I requested my tracking to be cancelled and I was transferred to cancellation department where I was Informed they will cancel the device however I have to give 20 days notice. I am not willing to give 20 days notice I am not going to pay for a service that I do get. I want it to be cancelled with immediate effect. I am not cancelling because I want want to I am cancelling because of poor service No service no pay.