What about calling 1K line and explaining the situation to someone there? Maybe that would be a better resort, since they should help a 1K with a situation like this. After all if not for the 1K, maybe OP's parents wouldn't have flown UA.

One time my wife had a UA problem so I phoned 1P line and got her a voucher over the phone. It helped to ease the pain.

The luggage situation is very unfortunate, but I think there's better luck with the 1K (in my case, 1P) phone line.

Good luck, and hope OP's parents were able to enjoy the rest of their holiday.

Michael

ps - how is it that if one buys Travelpro or Samsonite, that the bag can get repaired for free? Is a warranty required or is this the case when you buy the suitcase? Although I know that if one buys luggage or anything at Nordstrom's or Costco, it can be returned for any reason as long as the original receipt is kept. Then it gets claimed to the manufacturer, who already hedges for these by having higher retail list prices in the first place