Really poor client service

I am very very disappointed with the service i have received from your shop in brits mall. On the 10th of April I had opend an account with you at brits mall taking your 10mbps uncapped MONTH TO MONTH line and including a xbox for R230 @ 36 months. Now the lady that helped me did not tell me that if i take the package it becomes a fixed contract, she also did not read my contract to me nor read the terms and conditions to me she only said sign, sign, sign. She also never realy checked if we will have good signal where we live, when we got home and set up everything, it was fine for the first two days, then the trouble started, the internet became so slow that i cant even open my whatsapp on it. I went back to the store on the 20th asking them to only cancel the internet, i will continue paying for the xbox but they only said sorry we cant help you unless you pay the full cancelation amount of R8856 so by this time i was already furious, how can they expect me to pay R450 per month for internet that i cant use, i also cant pay the full amount once off, if i cloud i would have just baught a xbox at incredible. I have spoken to an agent on your online support and he said it has not been 30 days yet so i can take the device back to the store and they have to cancel my contract without any extra costs. Tried it yesterday 27 april, they just said the same that they cant cancel only my internet nor let me pay the amount off per month if i cancel the contract. So now I'm really fed up i expect you to cancel my internet and let me pay for the xbox only. Or you cancel my whole contract take the xbox back and i pay no extra fees, otherwise i can just go and see my attorney and take it further