No surprise about GTM being unhelpful. I had a long battle with them to get my HKS kit & was constantly lied to about stock & shipping They were great right up until the point they had my money, after that they couldn't care less.
Even whilst I was installing it they offered no response to the questions I had about the kit & the couple of small issues I ran into whilst fitting it.
The easiest way to get hold of Sam is to phone him.