When was the flight.

E+ fees are supposed to be refunded automatically if you paid for it, but in the end sat in a regular economy seat. It takes a few days though.

If it’s been longer than 1-2 weeks, then yes, you should definitely request a refund. On the refund tool, I believe you’ll be asked for a ticket number. You want to use the 016 ticket number that is listed on your credit card statement for the E+ charge - not the ticket number you flew on.

also, just to be clear, E+ on UA is not considered an ‘upgrade’ - it’s the same cabin as regular economy (even through you paid an extra fee). Don’t refer to it when dealing with UA as an ‘upgrade’ - it will just confuse them.