Why should I pay for the service that I am no longer receiving

I have singed up for a Vox Satellite and installation was done, the internet was very poor and I had to upgrade but still it very terrible. Upon cancellation they invoiced me for the duration of the contract of which I disrupted it and I was told that I need to pay the full amount even when I am not using their services. Fast forward now I have been summoned for the why because I have paid for the services I have received from Vox. I really don’t understand why should I pay the services that I am literally not utilising. This feels like a daylight ******* and my rights as a consumer has been violated. Kindly leave me alone as I don’t owe you anything, you took all your equipment upon cancellation and why should I pay the R23000-00 for the service I am nolonger receiving what kind of service provider is this, is it the one that was formed to ****** money from customers who are no longer receiving the services from them or what someone please balance me really quickly.