Cartrack, worst customer service ever

I had a 3 years contract with Cartrack which lapsed on 13th of March this year, from December I had to honour their contract and pay instalments when I sold the car cause they wanted R2650 for cancellation of contract when the remaining premiums equate to R720, now that the contract lapsed, they want me to pay R402 to cancel a contract that lapsed on March once again proving that they care about money not their clients, from December I paid for none service now they threatening me with blacklisting, no tracker, no car but they just want money from me, beware of cartrack, they exploit the vulnerable