Ahah!! Your mileage may vary!
I, too, could not figure this out, because the "idea" never said anything about that, so the 10% discount is assumed as an anytime discount. Sneaky!
Now see how easy it is to do the Bait and Switch?
At least companies will say it in the fine print!
When the debate is lost, slander becomes the tool of the losers. - Socrates