Sorry to hear about your problems. Sounds like one of those tradesmen from hell you see on TV. If it was purely lack of experience, anyone who cared about the work they do would have been very embarassed and would have bent over backwards to put things right.
Trouble with some of those websites is that people can get their mates to recommend them. You can't beat word of mouth. About 50% of my work comes from word of mouth only, and a job well done with a satisfied customer is the best advert you can have.
It does affirm my suspicions that those websites are a bit of a gimmick and I for one will definitely not be using them. Reputation is everything in this business.
Regarding the 3 way valve - even the most experienced plumbers are going to come across new things they don't know how to fit, but the only thing that matters is that they find out how to do it correctly and follow the manufacturers instructions.