I have a new build home that I have been trying to get the plumber to come back and fix several installation defects for over a year. One defect is an expensive repair as it involves redoing the shower liner, where the shower as the acrylic liner hasn't been glued properly to the wall so it is bulging out, so the liner needs replacing and redoing. The original plumbery initially agreed to come to fix the defects, but I discovered they weren't currently licensed and told them they need to be licensed otherwise they would be carrying out illegal plumbing work. I didn't hear back so I contacted them again and they ignored me until they eventually responded to say they wouldn't be doing anything. They currently aren't licensed to do the work anyway. I believe I have given them enough opportunity to fix it.  So I have got another plumber to provide a quote for the work and report eh defects on the quote which they charged me for. I contacted several plumbers, but some didn't want to do the work because they didn't want to fix defective work from another plumber, and another plumber I contacted never showed up to quote. 

I am going to get the immediate defects fixed first. As the shower is going to cost thousands to repair, I was thinking that it maybe better to take the plumber to the disputes tribunal first with the quote, and get the money off the plumber to pay for it before I got the work done. Also it potentially gives him a final opportunity to do the work. Does this sound like a good idea, or is it better to go to the disputes tribunal after I have got everything repaired? My fear is that they may claim the repair cost was too high if I get the shower repaired now, and I only end up with a part payment to pay for it. But if I get to done afterwards, there maybe extra cost in plastering and paintwork around the shower if they don't get the liner off cleanly which aren't allowed for in the quote.

TIA