I was going to have one fitted but to be honest, the bad reviews have stopped me. I appreciate some are quite happy with their roof and i suppose it is in part down to the fitter. However, I am not willing to take that chance, parting with over 4k and having no end support.
Is it not possible to take them to the small claims court? Take pictures, write down every conversation / phone call you have had to rectify the issue. I once did that with an expensive caravan cover and was successful. Yes, had to attend court.....but they would probably give in before that or wont attend court. If they dont attend....you win.
If it was me, I would be on with it immediately.
Whatever you decide, good luck.