Proper bike mechanics who know what they're doing...how can I find one?

Just like with shop assistants DECENT mechanics are rare as the wages aren't attractive enough to attract lots of sensible people for long enough. Many of them will leave for a better paid job before getting enough experience.

Also many shop owners tend to prefer youngsters with worthless "bike mechanic" certificates so they can proudly claim that they employ "qualified bike technicians" while paying them peanuts at the same time.

Contrary to all the propaganda bike maintenance training certificates are a joke and say absolutely nothing about anyone's qualifications. They only benefit companies running the courses.

There is no substitute for the right mix of experience, passion, geekiness and a some IQ but you're not going to come across it very often.

While I wouldn't wish to make excuses for sloppy work, bear in mind that no-one's perfect. I'd go back and mention it and see what he says.

In my experience proficient mechanics come in two flavours - those who do it for a living and care about their work; and those who love working on their own bikes. Fortunately I have a good LBS and a neighbour who builds his own bikes. I had issues with the sloppiness of the 'trained mechanic' at another shop in town so I don't go there any more. Don't take a certificate as proof of competence.

It's very satisfying to have confidence that you can sort most jobs out yourself. Experience, forums, websites like Park Tool and Weldtite as well as videos on Youtube and http://bicycletutor.com/ have helped me.
The Comic has just put a 7 best maintenance books article online too.

As a professional mechanic, there is both actual and implied liability for the work performed. I have worked in the cycling and motorcycle industry as a professional technician and always adhered to the " safety first " approach of repairs. We have a duty to point out any possible dangerous conditions and double check our work for accuracy. Any form of transportation can pose a risk of injury or death when neglected. You should bring this to his attention, perhaps saving another cyclist from disaster.

at least go and tell them, dont make a scene but he at least owes you a big favour

I have mixed views on your post.
A basic service for £30 will not be extensive but it will cover the safety of the bike. If anything else is needed but not covered by the service it should be reported to the customer in a professional manner. If done well it gives the customer confidence and is good business practice.
You have every right to go back and complain in fact you should,try turning a negative into a positive, if it was a one off and he is decent he should bend over backwards to keep your custom.
Your post makes it clear you and hubby clearly need help with bike set up, so give him a chance to cultivate a fruitful relationship that will be of mutual benefit.

You are right, surely you get your bike serviced so that you don't have problems? Not to assess their lack of ability? How much did they charge to wreck your bike?

Look for a Cytech accreditation from a mechanic/shop. It's the nearest thing to a profession/industry standard. See:

http://www.thecyclingexperts.co.uk/cytech/

Useful search facility...

Get it back, ride it, find problems, take it back to the shop. Bike services normally have a few problems when you get it back.