I had to cancel a return flight after I had already flown outbound. I spoke to an agent who assured me that I could receive partial flight credit, although, understandably, he couldn't tell me exactly how much, since it was a partial cancellation of a ticket. I assume it has to go through some actuarial system to figure out how much to refund.

Fast forward to four weeks later. I don't see any credit associated with the itinerary, and when I click the "use future flight credit" link, the site issues an error saying "We are unable to complete your change on united.com."

Does anyone know what the process is to acquire and use this credit?