"Single game ticket holders, who purchased through nationals.com, choosing to use their rain check ticket for a different 2018 regular season game must bring their ticket from the cancelled game to the Nationals Park Box Office for processing."
What a pain in the ass.
Just bring the old ticket to the game you want to exchange, trade the tickets in and walk right into the game. No need to make a separate trip. The remaining games after this series with the Cubs aren’t gonna sell out, and the games today/tomorrow are already down to minimal selection so you weren’t gonna get those anyway.
I exchanged at the ticket window last night, took all of 4 minutes.
