,,,I was told the reservation department wasn't able to override the incorrect pricing, and they were unwilling to contact the tech department to help me figure out the root cause of the issue.....
From the original description, you wanted to change one segment and but not change another segment (which no longer had availability). That can be a very problematic request for awards. Sometimes it works, sometimes it does. It is a downside of awards that the change of a complexity partner order is not an option It is surprising UA even was willing to try. In general once booked, changing a portion of an award may not be an option and should not be counted on. This thread is full of cases people ended up award trips with missing unrecoverable segments.