Had exactly this at the two Hammersmiths a couple or so years back.
Told at H&C have to go to National Rail station... um, no...
Walked over to D&P (the alternative entrance/exit by Tesco Metro), no problem.
Ditto at the former Euston TFL shop a couple of years back. Before I got to the counter, I was intercepted by a queue minder who sent me on my way, telling me they don’t do this any more. He was unable to offer any further advice.
I walked around to Pancakes and got it done there. No problems, no quibble.