Terrible Service at Altech Nestar

I have been a client with your company 2017. I purchased a car in the beginning of the year and installed your service at time of purchase. I then sold the car in September 2017. When I contacted your company with regards to cancelling my subscription, I was told there was a fee of about R1500 seeing as I had been a client for less than a year. I was okay with that amount. The car was sold and yet I continued to pay for the service. Last year November 2018, obviously more than a year since I've been with Nestar, I called again to cancel but was told ONCE AGAIN that I will have to pay a fee. That fee was also much more than the original R1500 quoted to me. I have been in contact with a woman called Miriam who refuses to cancel my subscription and give me a tangible reason as to why I have to pay this fee. She then gave me an email address to which I sent an email around November and up til today I have received no response. So I took matters into my own hands and decided to cancel the debit order so I no longer have to pay them. Without my knowledge, the company changed their reference and still deducted the money from my account! Working with this company has been a nightmare and I recommended no body to work with them.