Hmmm, added poking around revealed that the "sponsor" is a notorious time-share sales company here. In a local forum I posted this same query on, someone related that a friend of his was pressured into signing up for an $8,000 time-share, all the while the guy and his wife weren't allowed to leave nor to use the washroom, nor even to use their mobile phones to consult anyone.
My reaction is, if they pull a stunt like that on me, I'll sue for false imprisonment
(yes, IAAL so it won't cost me much to do it). Better yet, hand out my namecard to the other victims and start a class-action lawsuit
Nah, I've got better things to do with my time. Thanks for the input; I guess additional comments would still be appreciated, for the benefit of anyone else who ever purports to win vouchers for use at woarewards? From my subsequent googling, in the US this seems to be typically in association with car dealerships, where you get a scratch-and-win card.