Poor service and refusal to replace phone

Had Samsung S6 for just over 2 months, took it to the repair store as it switched off and wouldn't turn back on. After two weeks of almost no feedback from them popped in on Friday (27th) to find out what's going on and luckily phone was supposedly fixed. It did switch on in the store. Took it home inserted sim card and wouldn't pick up a signal at all. Put it on to charge as it was almost dead, it switched off again and wouldn't switch on. So either the tech doesn't know what he's doing or you didn't bother repairing it at all. Took it back Sat (28th) was told by tech he would phone me within an hour its 48hours later and no response. Store didn't answer it's phone the whole of Sat or Sun. Phoned again this morning, they have no idea of what's happening with the phone and need to try trace it....really....I refuse to accept a 2 month old phone that needs to be constantly repaired. You are in breach of contract and need to replace the device. You have already attempted to repair it once. No more. Consumers have rights go read the Consumer Protection Act. Over and above this I will be expected to pay for a contract that I haven't been able to use for over two weeks. I want a refund