Unfortunately the trade associations were who we had to go with to get ours "remedied" because it wasnt us who has it installed. And we've still got an install i am unhappy with and will be changing myself.
Id strongly suggest using the threat of the trade assocs but exhausting every other opportunity first.
They will just act as an independent, impartial mediator between the two parties.
No legal recourse can be sought before you go that route or they wont take the case on.
You have to agree to let them decide what is good enough and have them oversee the remedial work. You then have to agree to accept what they find as binding and final.
If they find there is a case, and the company refuse to put it right then the company are reprimanded and or removed from that association, and only some will make sure the work is then carried out to rectify.
Thats as far as they take it.
Our experience showed me that they are happy to sign off on what scrapes the barrel for a pass.
Far from the heatgeek experience Ronski signed up for, though heatgeek may be the only trade assoc recourse worth persuing as they have made their name off of their guarantee.
At least with the money held back, an almighty stink can be kicked up.
The problem is all trust has now gone. And taking an entire week off work to watch everything they do to fix it, is a big problem in its own right.
Brains had a fart whilst getting annoyed about what you are going through. 
