Equipment does not work, wont refund

I have been battling with Mobile Repeater SA/Signal Booster since October 2015. I first bought a 4G booster and followed the installation instructions. It worked perfectly and had 100% reception in my office. I was so impressed that I asked if I could swap it for a dual unit that boosts voice and data. So after paying about R5500 I install a dual unit that does nothing for either voice or data!!! My frustration is terrible because all Dominique says is that my installation is wrong. If it is wrong then why did my first unit work so perfectly? Dominique is full of promises until the sale is through, then he drops you like a sack of potatoes, dont expect after sales service. I am not getting any value out of their product (in fact it is all packed up in my cupboard now) and just want my money back (AS THEY PROMISE A 14 DAY MONEY BACK GUARANTEE). Please keep in mind that I have been battling this via phone and email from Cape Town. I am extremely disappointed and expected so much more.