I've found that Stillen is probably the best, most up-front, honest company I've dealt with on these forums. I think "Kenny" needs a lesson in customer service though. I've also spent a lot of cash with them and have always been treated with respect and integrity.
Your account.....?
AND, I also think that the issue with your splitter is probably not their fault. You should probably go after the shop who installed it in the first place. Sounds to me like if there was any fault, it would lie with them (Not Stillen).