Ask HN: How Do You Deal With Companies That Balk On Guarantees?

Recently booked a trip on Expedia when my wife discovered a lower price on Priceline. She then discovered that Expedia had a "Best Price Guarantee". Supposedly, with this "guarantee" you get the difference back, plus a $50 travel voucher. After submitting the claim form, we quickly received a canned response from Expedia that stated we'd used a guest checkout to make the purchase, instead of being signed-on to an Expedia account. Supposedly, per their terms, only the latter qualified for the guarantee. I first pointed out that I actually have an Expedia account under the same e-mail address with which we booked, but just didn't happen to be signed in. No dice. Then we noticed the real problem: This supposed restriction is actually nowhere to be found on their site, including the very specific Terms & Conditions of the guarantee: http://www.expedia.com/p/info-other/guarantees.htm (click Terms & Conditions link on that page) When we pointed this out over a couple subsequent e-mail exchanges, some guy named "Luther" just kept copying and pasting the same reply: "We apologize for the inconvenience this may cause you. We are unable to process your Best Price Guarantee request, since we are only allowed to process Best Price Guarantee claims for reservations that was booked under regular Expedia.com account. We do sympathize with your situation and wish we were in a position to do more; however, we need to comply with the rules and restrictions of the Best Price Guarantee program." It seems that this program and their handling of it is specifically designed to enrage customers by offering something then reneging, with exclusions and undefined "gotchas", then repetitive responses, clearly intended to frustrate. Has anyone else encountered this with Expedia or similar with other companies' "guarantees"? How did you deal with it?