Originally Posted by bocastephen

The self serve tool is the only option - United has not provided any tools for agent to search for, or process *A upgrades. This is pretty consistent with most members, they seem to offer up *A upgrades very grudgingly and have no interest in making it easier for consumers to grab these.

Basically you would need to cancel/refund the ticket and start over with a new reservation and new ticket. How did you issue the ticket? This is why using a brick and mortar agent is almost essential for making this process work smoothly, although I've honestly lost too much hair dealing with it.