Cancellation of contract

I took up a deal with Vodacom for home wifi within the first weekend i saw that the connection is very weak at home and wanted to cancel the deal as it is not working i went back to the branch in Upington as i am based in Upington they asked me to provide them with screenshots of speed tests that took for them to see that the signal is very week and i decided that I want to cancel the whole deal and they advised me at the branch that they can't assist me with the cancellation in the branch i need to call the call center witch I did and then the call center said that they can't cancel the deal either because I did not take up the deal online i did it instore and they should cancel it went back to the store and they still did not want to assist me as they do not do cancellations instore I was sent back and forth and i had to pay two premiums of something that i cant use i am verry unhappy with the service and want it to be sorted out please assist me with my predicament thank you.