i understand exactly where the OP is coming from; in trying to get a deal i would consider doing the exact same. if there is a way to save 3 x the difference in price on your holiday it can run into a considerable amount, and you would be silly not to consider this.
some people go to great lengths to do similar with price match in supermarkets, so why should trying this with a holiday company be any different.
the one thing however is that if you want to play this game you have to ensure that you follow all the terms and conditions exactly as stated. this is the major reason these claims fail and the company gets out of paying.
it is a great advertising gimmick to offer 3 times the difference, and if you don't have to pay out it is even better.
so, while i think the idea was great that you tried to take advantage of this deal i am afraid that you have probably come unstuck by not following the conditions exactly.
a screenshot is exactly what it says - a (snap)shot of the screen.
you did not do this, so i think you have lost your gamble.
i would still try the sympathy approach, and explain to them that you possibly misunderstood their definition and offer to settle for a price match so you would still get the holiday for the cheapest price, but that would be at their discretion.
look on it as a (
) lesson learned.