Very dodgy "plumber"

My insurance nominated PW plumbing to come and take care of an issue at my house, after a few delays and postponements Rayno arrived (without and tools etc) and assessed the problem, I was not totally in agreement with his advice but I am no expert so I agreed. They dug up my garden to replace a section of pipe that was supposedly causing the problem and advised that once the air was out of the pipe it would be fixed (it was not the same problem persisted). While they were there I asked them about a pressure valve that seemed to be dripping excessively, they advised that it needed to be replaced but i needed to pay them now in order for them to buy the part (which I did). Since then I have called repeatedly for them to come and install the pressure valve which I have paid for and to sort out the problem which is not fixed but Rayno stopped taking my calls, when I call from another line they answer with 101 excuses why they never took the call from my number and promising to be there the following day but they never show. I now can not get hold of any of them and it seems that they have taken my money and disappeared.