An interesting question came up on Travel Stack Exchange. I was about to post a simple answer about how to get an excess at Paddington, but then I noticed that OP had said they hold a mobile ticket. Never having used one of those myself, it made me wonder.
My gut instinct says that getting an Excess on a mobile ticket, while perhaps not technically impossible, is going to be so hard that it may as well be. Or am I wrong? Will a ticket office just sell you an excess no problem if you hold a mobile ticket? Or is there another way to go about it? One answer below suggested you can change the ticket through the GWR website but that this will incur an admin fee. This to me sounds more like the procedure for changing an advance than an actual excess though.
My gut instinct says that getting an Excess on a mobile ticket, while perhaps not technically impossible, is going to be so hard that it may as well be. Or am I wrong? Will a ticket office just sell you an excess no problem if you hold a mobile ticket? Or is there another way to go about it? One answer below suggested you can change the ticket through the GWR website but that this will incur an admin fee. This to me sounds more like the procedure for changing an advance than an actual excess though.