I booked a flight for this summer earlier today, ticketed by company travel agent, each ticket was a W fare. I have a $500 voucher (16TCVA variety) so I figured I'd spend it on upgrading the tickets to first. Both flights have P fares available, and the difference in price from W to P is around $300 each way. So my plan was to use the $500 certificate (it's just like cash, right?) and supplement with $100 on my credit card.

Called the 1k line and got an agent who understood what I was trying to do. But 20 minutes later, after trying to enter the cert and my credit card, then my credit card followed by the cert, said that the voucher could only be use if it covered the entire cost of the upgrade. So I had her only upgrade me on the return leg, and now have $200 left on the voucher.

Is this a HUACA situation? It just seems really odd to me that they can use vouchers plus credit card if I'm buying trips for my family on .bomb, but a United 1k call line agent is incapable of combining a voucher plus credit card for a buy-up upgrade within the 24 hour of purchase window.

Thoughts, advice, experience? Maybe I'll call back and try to upgrade the outbound leg separately with a different agent?

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Update - the next morning: I called the 1k line back and specifically asked about an upgrade with credit card plus certificate. The agent immediately told me that a certificate for a re-issued ticket must cover the entire cost, no combining with a credit card. So that's the nuance: You can combine on a new purchase, but not on a re-issued ticket. This is an important nuance for those of us who want to upgrade company travel agent purchased tickets.