Selling us LTE wifi that doesn't cover our area

We received a phonecall(cold calling) from a very nice gentlemen from Mobile talk selling us a LTE wifi. Everything sounded great, the fast speed the affordable package so needless to say we went with it. The unit(Huawei) was delivered a few days later and this is where the nightmare started. I had to phone a call centre to help me set it up. I was put through to various people and had to phone back a few times and send complaint and pleading emails and until today, no reply. I was speaking to a more experienced person last week who set me up after I told her that the internet seems very slow. But I believed her that everything was working now. On Sat morning I called again because we have not been able to use the internet for the 3 weeks we've had it. After calling the call centre again I got put through to the same department, but the lady that I spoke to this time asked me what my adress was, and I gave it to her. She said, 'sorry mam, but you have no coverage in your area.' How do you sell something that doesn't work.????? And it is the end of Monday and no one has contacted us regarding the matter. We told them to collect the product and we want a refund. Very unhappy!