False advertising and poor service

On Monday 29 Feb 2016 I asked the consultant if they have the network coverage where I stay in Karino and he said yes, I then decided to buy the tablet however when I got home the was no network coverage. I called the helpline and they told me what to do for it to connect but nothing happened. So on Thursday I went back to return it and Nonhle gave me attitude from hell, she took the phone and said the manager will call me back. Then on Friday Nonhle calls me and says they wont cancel the contract because there's no proof that there's no coverage where I stay, why would I lie because I wanted the tablet and what am I supposed to do with it ? I went there because I needed that tablet and now it is useless.