My friend was given 4 500-mile paper upgrades at the airport and was told she can convert them to 2000 united miles if she wants. she has no status on UA and can only use them on higher fares, which she will never buy. since she is 1700 miles away from an award ticket that she needs, i told her to just trade them in vs buying the 2k from united. can she go to the airport to turn them in or will she have to mail them. thanks