Vodacom net work provider

Good day please note that vodacom has contacted me, however they are not very helpful. I asked them to deactive my contract Sim card so I can pay for the phone, with the installment that we agreed on, they response is that I am now in areas, they are unable to deactivate the Sim is there any way which you may assist me, as vodacom wants me to pay the amounts which are in areas, but it was not part of our agreement. The agreement was that I will pay a fixed amount of R199. 99