Collection of R600/month 18 months after the contract was expired and discontinued.

I have been handed over to debt collectors, who are demanding money in 48 hours. My 2 year contract ended about 18 months ago. I have told the lady who phoned me when my contract ended that I no longer wanted the netstar. I only signed a netstar contract because I was forced to when I bought my three cars. Netstar have been deducting about R600 per month for the last 18 months *******ly from my account. I have been forced to freeze my account in order to stop these ******* forced deductions. Now they are forcing me to pay with their lawyers / debt collectors. I want them to immediately cancel my account back dated to when the two years expired. To repay me immediately all monies that were *******ly collected. To remove my name from the collection agencies and to remove the tracking devices from my cars which are running the bateries flat.