Cancelling tracker services

I had the best service from Matrix whenever I needed their service's that I do not wanna lie. The problem started when I wanted to cancel the tracker service since I no longer have the vehicle. I sent an email letting them know that I sold the car. I got the shock of my life. Ok this is what shocking me the most was that it was my first time insuring my car so when they introduced me to matrix I didn’t have any problems the price was reasonable. They then suggested a Beam I didn’t know how it worked but as I was browsing on Facebook I saw matrix with a more advanced system that included a panic button well since I am a new driver I opted for that one. I then called matrix & asked that they cancel the beam & give me the one with the panic button. The lady was like sure we will. I have to phone several times to ask them to come & install the new one. Fine the guy came & everything was fine. I then sold the car & immediately sent an email letting them know them BOOOOOOOOOOOM the beam appears as well I must settle it as well as the new one that was installed. I’m told on email I must pay over R3000 to cancel it. This is insane why was I never told in the beginning of those hidden fees. I am very angry & disappointed & I will never use their services ever or recommend anyone.