Sweets.
motor dealers are not responsible for designing or manufacturing cars or deciding what materials to use in production, but whenever things go wrong it's always us who take the flak instead of the real culprit's, the manufacturers. Coming on here slagging us off collectively what does it really achieve? Yes it lets you vent off some steam and wind up a few genuine dealers. I would firstly approach Vauxhall to see if they can help, after all a network Q warranty is a Vauxhall product, if you don't get any joy then try watchdog.
Good luck with your problem, do keep us informed as we hate to see customers getting mistreated by rogue dealers in our industry and would love to stamp them out just as much as you.