This is why you get told to get more than one quote. A single brick wall is 100mm thick, and with a 15mm pipe, you'd need to cut in about 25 maybe 30mm, so you're not going to be weakening the wall. If the plumber has a channeling machine and a wet and dry vac, then there shouldn't be too much dust, and it's damn quick. If he hasn't got the equipment, and you can handle the dust, then a 125mm angle grinder and a diamond blade will cut the channel just as well. Then you wrap the pipes in the foam or material pipe wrap, drop them into the walls, and just use a couple of nails to hold them in place whilst you cement them in.
Basically, he didn't do what you wanted, and then didn't even do what he said he was going to do, so there's no real reason to pay him for the work. Broken contract on his part.