Smart Travel and Incentives As close to a scam as it can be while looking legitimate Lake Mary, Florida

I attended a sales presentation on discounted travel deals in ealy March but was unconvinced   that signing up at that time (for a deposit of $6K to $8k) was a good deal since I am still working and don't have sufficient vacation time to really take advantage of mutiple vacations in any one year.
The invitation to attend  was supported by an offe of a free round-trip airfare and Marriott stay for which a voucher was given at the conclusion of the presentation. I returned the voucher together with a Cashier's check for $100 as requested to register within the 21 day period. This was received by ST&I on 26 March. Today (May 11th) I had the check returned (for which I'm at the very least grateful) and was informed that the activation was void because I had not sent the check via certified mail and this was a condition of their Terms and Coinditions.
This report is simply to warn others attending these presentations. This seems as close to a scam as it dare be, yet is, I suppose, legal. There is no telephone or web address to contact ST&I and discuss the issue. I am of the opinion they hope that the majority of attendees applying for activation will give-up, as I intend to do. ... but please be warned.  Read the small print carefully and comply with every small detail!