I was not really surprised by the denial but wanted to add a data point. I submitted a Best Price Claim last Monday as the flight I booked was cheaper on various websites. According to the T&C's, I should have received a reply within 72 hours. In reality it took over 120 hours (two full extra days) before I received a response. I expected the cheaper fare by then would not be available, and verifiable, any more. However as noted up thread it was the following condition that resulted in a denial: "The Third Party Fare must be available from a website of a company that is based in the same country of departure as the Purchased Fare. Check carefully in the "About Us" or "Contact Us" (or similar) page of the website to check that the company is based in the same country of departure."

Of course nowadays in the world of online commerce this is a nonsensical requirement. Major booking platforms have local sites for each individual country but indeed if you dig into the place of business of the parent company, only a few countries remain.