I generally find that
"I must really not understand this rule, would you mind calling a floor to explain it? I've had it told me different ways before." or something of the sort works well.
Gives the dealer a chance to save a bit of face by claiming that he it might have been different in the past (even though we know it wasn't) and it generally keeps the vibe at the table less hostile and more easy going.
Quote:
1. If there's any ambiguity pending, you shouldn't take any action, even if the ruling doesn't affect your decision.
And this.
I just wait. Simple things like "I don't mind waiting a few seconds, I don't want to start a cascade of action." works well. People nod, they've all been there. They understand.