how to convince potential players of a fundamental rule?

[rminusq]

At Harrah's AC, a tourney table tried to botch it. Blinds of 300/600, player says raise and thows out a 1000 and next player calls. I say "It has to be 1200." First they fix it, then say "No, we can go to 900 because the big blind is a raise of 300 on the small blind." They convince the dealer! I'd already folded UTG (so I don't know if this makes me a dick), but when the dealer asked if I wanted to call the floor to confirm, I said yes, and the floor said it had to be 1200. Then other side of the table, they thought the next raise had to double it again to 2400.