Paying for a service that doesn't exist!

I tested my device early in Jan and was informed that it was not working, and thus informed (9 Jan) I will have to pay the service fee of R395 to replace it. I informed them (be email) 4 days later that it must please be replaced, but no response. I emailed a request again on 20 Jan, with no response. I logged a complaint on their website around 24 Jan regarding this situation, no response. <br> <br> So as it stands I have been paying for a unit that is not working, so my insurance on my car is void if something happens. Even though I have requested for the unit to be replaced, this has not happened - I am paying for a service that doesn't exist!<br> <br> I will stop all payments until this issue is rectified.<br>