Blacklisted for Money NOT owed, **** about my tracker removed..

After driving without a tracker for 18 months, because my car's battery was dead numerous times, i finally decided to end the contract. Cartrack notified me that they'll send a technician to remove the tracker, which will cost me R 600 - I told them it was removed 18 months ago, they don't need to. They kept on harassing me about the tracker - the consultants' listening skills are appalling. I finally said I'll go the Durban Road branch for them to look if it was still in the car. The lady came to me eventually, telling me the tracker was removed. I told her she's lying, because it was removed 18 months before. She kept insisting they removed it, to which i asked her if she is lying, or the person 18 months ago, who, at the SAME branch, told me the tracker was removed. I left the reception area, saying loud and clear - no wonder so many people are moving to other Tracker companies - which I heard from a source in the motor industry a month before. I was paid up, I did not get a technician out, so I owed Cartrack R 0. Today I received a SMS that I was blacklisted by Cartrack, because I owed them R 752. I've replied to their emails, stopped answering their calls, because there is NO way that I owe them that amount. I refused to take any more Cartrack calls, because they were hacked and all their customers' details, including bank details and addresses, was accessed by the hackers. I am still convinced it was the hackers trying to make money from me, but the BlackListed SMS now makes me wonder. Cartrack - *****, unreliable IT procedures and structures. Which makes me think their accounting is not much better.