I am flying from lhr-cph on sun, 26 aug. We hace a ua gold with us, and I know that a guarenteed benefit is priority waitlist and standby. We want to go on an earlier flight than we are on. However, sas in the us said to buy new tickets, and in cph they said that that's not a benefit, and that it was impossible. First, is it possible? Second, will the people in london feel in my favor? It would be great to get there earlier.