Out of interest what is the job? sounds like it's a bit of a nightmare and the tradesmen don't want to get involved. they should just come out and say that, if thats the case.
It's a long story but partly involves a combi-boiler and a booster pump, two pretty common things but both beyond the ken of the plumbers we've encountered.
And you're right- in some cases they just didn't want to get involved, which is a rich position for a professional. We all have our trades- in the service industry myself- and I just can't believe the consistently cavalier attitude to customers. You end up like the original poster hoping for some competition (or a slowdown) to put manners on them.