I'd like to know the reason behind the change in accomplices before making accusations of bait & switch. If it's because of some players complaining because they don't like the change (and/or threatening to stop buying gold because of it) then let's be honest, it's those players to blame 60% and the company 40% for not calling their bluff.
If Gree have decided that it just wasn't working as intended, then the case for partial refunds is stronger. But nobody should be refunded for doing events that they would have spent on anyway unless they're prepared to lose all the prizes from that event.
More dubious is the idea of someone buying a load of gold, waiting for their bonus to be delivered and then getting a refund from their vendor. That's sailing much closer to fraudulent behaviour than anything the company has done to date on this subject.