Car track *****ing my money.

My vehicle had an electrical issue during my vacation break in December. VW narrowed the cause to one of two car tracking units. They informed me that I need to call the technician for the respecting tracking company to come disconnect, to test the unit if it is causing the issue. This was arranged after some difficulty and the Technician came out the 28th of January 2021. Since then, I have tried making contact with Car track via webpage, call centre and email. Only when I requested to cancel my contract they responded via telephone and sent a technician to my house. Upon the technician arrival he informed me that the GPS "IO module" was not fitted nor was the fuses that powers the unit in. Car track then called me to inform me that I will be liable for the cost, which I declined as the unit was offline since 29th of January. Thus my suspicion that the technician never installed the unit back in January. My vehicle was with me since then, with no one installing anything inside or outside for the last 6 months, so how did it disappear? I instructed Cartrack to send me the "Log-file" for my tracking unit and also the technicians' report from January. It has been now 10days with only telephone calls but no email with info that will back someone's story. If this is not resolved by 1st week in June I will take all my vehicles and those of my relatives from Car track.