so i have to top up my oyster card with some extra cash for when i am down in a few weeks, so here's a thing. i can do it online and pop it on the card, but it needs to be "validated" at a station. so, how do you do that? is there any benefit to that than just scanning it and adding it at the station anyway?

oyster is pretty complicated. the whole fucking TFL thing is pretty complicated, no idea how non-English speaking tourists manage it.