This sounds very arrogant. Carmina doesn't owe you anything, and just because you have bought from them in the past does not mean that they should make exceptions for you. There was no actual GMTO going, (there weren't even 6 members in for it) plus Steve had said before that he didn't know if Carmina stocked the leather, but he had to confirm, its not like carmina led you on at all.
Also, you cannot just insult the company, come up with some oblique excuse, and then just say "i will leave it at that" like the matter is satisfied.
Wasn't involved with the original situation, but given these details, I have to agree. Disappointment? Totally understood. But insulting the company isn't called for.