Netstar and Hybrid Collections

I had a tracker with Netstar for more than 2 years, then cancelled the service. Netstar then proceeded to charge me for 2 more months after cancellation. After I sent screen shots of the cancellation and numerous calls, I received an email stating that my account is closed and all payments up to date. BUT! They handed me over to Hybrid Collections, and according to them I still owe them R213.15. This Company is harassing me, and I have sent numerous emails with the Netstar confirmation but get no response from them. I will never trust Netstar again, and to hand me over for R213.15 and them being in the wrong. They even threatened to blacklist me for an account that is up to date! What am I supposed to do now?