As a regular punter, I've always used "official" plumbers, even tried once to use plumbers that belong to some Guild or other (CIPHE).
I've lost count of the amount of times I've taken a day off work to wait for a plumber who didn't turn up at the scheduled time, or even at all, wasting me a days work. That's annoying, but bad workmanship and incompetence is worse:
Three years ago, I moved house and employed a local CIPHE Gas Safe/Corgi plumber to remodel my bathroom and fit a new boiler.
If I hadn't have been home on a couple of occasions he would, quite literally, have flooded the house due to lack of care (radiators with open valves while filling up system, for example). He trashed a new carpet due to lack of adequate protection, fitted a window with no cills, cocked up tiling three times, gouged a huge hole in the kitchen wall below the bathroom while fitting a shower waste, chipped a radiator before AND after installation and attempted to fit a shower cubicle TWICE to a wall that wasn't true (his wall), which leaked and destroyed a new laminate floor. The list goes on. He visited 12 times to try and repair the leak before stripping the whole thing down, retiling and refitting the enclosure. It still leaked. He claimed 25 years experience in plumbing, had a registered company and a fleet of vans, but couldn't fit a shower that didn't leak?
I complained to CIPHE - Absolutely useless. A trading association masquerading as some sort of regulatory body imho. I threatened the original plumber with legal action and he paid for someone else to redo the shower.
I then contacted 3 CIPHE plumbers for an estimate. The first came round and didn't even look at the job, just dissed the other plumber and the stuff he's put in. The second suggested some strips of plastic against the shower cubicle (on the brand new shower that was leaking from below). The third failed to turn up.
I then contacted a plumber that I found on this site. He had all the tiling stripped, the wall replastered, the tiling redone and a new shower enclosure fitted. During this work he found that the original plumber had used the wrong type of adhesive for the tiles, and that water had got behind the tiles. This remedial work was finished in August 2009.
In October 2010, the shower started to leak from behind. I contacted the last used plumber (he seemed pretty good) At that point I had no reason to believe that it was his responsibility to repair, and didn't ask for free work.- No response to online forms on his site or emails. Eventually, just before Christmas I received a reply "very busy, contact us after Christmas". Fair enough. Multiple emails after Christmas were unanswered, so I gave up and found another plumber.
This latest plumber has now found that the work done by the previous plumber wasn't up to scratch, causing long term leakage behind the tiles which has seeped down into the kitchen and underneath the vinyl in the bathroom. The grouting has all but gone, and the sealant wasn't (apparently) of good enough quality. I've just paid this latest plumber to redo the grouting and reseal the shower not much more than a year after the job that was supposed to have been done properly.
Now, each time I've used local established firms with apparently good track records. Most have been members of some guild or other. All have been Gas Safe and Corgi. It's not been cheap, but then I don't mind paying a fair price for a fair job.
The problem is, I've never yet met a plumber who could actually do their job properly, but who has no problem with taking the going rate for a job. I understand that plumbing isn't a precise science, but how many plumbers does it take to fit a shower properly? You're only as good as your last job, and in my experience, there are a lot of shoddy workmen out there who's last job was awful. I have no confidence in anyone in the plumbing trade and imho there's no regulatory body that can deal with the supposedly legit people who can't do a job properly.
I did once employ a couple of eastern Europeans to do some general building and labouring. Advantages over the local blokes? Cheaper, cleaner, always on time and did a sturdy long lasting job.
Given the choice between a kosher plumber with letters after his name and a shiny website, who will charge the full going rate, turn in shoddy work and then ignore me, or a "risky" eastern European who charges less and usually does a better job with less mess and less moaning, which do you think I'll choose next time?
Of course, when it comes to gas work, then I would always employ someone who was registered Gas Safe (and I think I may have at last found a decent heating engineer), but tbh that's more to do with legal requirements than that I think that someone who can put a logo on their website is any more competent than someone who isn't "registered".
I'm sure that there are decent, competent plumbers out there, just not found one yet.
If you're losing work to eastern Europeans, then it's down to the officially sanctioned charlatans that make the average customer like me go for the cheaper option. If my house gets flooded, then at least I've not paid through the nose and wasted hours of my working time for the privilege.