This looks like it's coming in all over the network, and we in the UK have had these fees for some time now - see this
AskBA page from ba.com.
It's not a fare increase because for the most part you can avoid it by booking on the Internet, which is what the airline would like you to do.
It is
irritating, though, when you have to pay it for simple transactions that the website cannot handle - like open-jaw-at-destination tickets, which seem perpetually to take the BA techies by surprise.