Val, I agree, nothings worth than a let down when you've booked something. The group buy is mutually beneficial, so we are getting a favour with the price and he is getting a favour with our custom.
I'd just keep things a bit more neutral when speaking out in public on the board about the guy, thats all.
Stephen is right, tuning 5 cars in 1 day is nigh on impossible, especially with the FI fella's there as well.
One thing i would check is backup and support, as some people in the US have tried to get a group buy on the UTEC, and it seems TurboXS dont want to know regarding support for products that have been purchased with a group buy. Might be worth checking out.