You're welcome my friend, enjoy the savings.
Make sure they do it for the right date, and apply the railcard discount (if relevant) before leaving the ticket office. They get both of these wrong, a lot.
Thanks Xanoas, that's handy to know.
You can also buy PlusBus tickets after collecting your tickets at the station, just go to the ticket office and ask for PlusBus tickets.
Thameslinks app and site is a good place to buy tickets with plusbus, even though their actual service is rubbish.