Demanding money for a service I never receive

I bought a car in February 2025, the dealership told me that Cartrack will install a tracking device before I pick the car. Then when I collect the car, I signed a Cartrack contract thinking that a device have been installed. They deducted R169 end of February and end of March. On the 2nd of March I received a call from The car dealer saying that Cartrack is asking ne to bring the car so they can instal a device. I asked the lady from the dealer of why bcos they told me that a device was installed. She said no, the Cartrack guy never come. I was shocked that means i **** to my insurance that I have a tracker. I told the lady that I'm no longer interested, I will join my own. Now Cartrack is busy threatening me saying they are going to blacklist me unless I pay them for installments of 3months. What if I was Car-jacked while I was 100% sure that I'm covered. They are now calling me demanding money for a service I never receive.