Unused service from NETSTAR

Good day, I am so annoyed with NETSTAR. They claim to have installed tracker on my car in 2018 or so and that car I gave it to my sister in 2012 and it is not insured. I've asked them to sent me the installation certificate which was done in 2018 and they could not provide me with since there is no such. Now they are billing me and threatening to blacklist me for something that I do not have, like i did not use the service since then and they cannot even tell me currently where the car is. The past 6 months where the car have being parker and this is really not cool. I have requested all the date and all and still nothing from them and i cannot take anymore. They send me to Hybridcollection for the premium as I write this review that I am not paying them what is due .