I'm sure I remember seeing a British comedy sketch back when I was at Uni, where someone was threatening to beat another guy up and said that he was going to 'enhance' his face. The details are vague but maybe A3 staff saw a similar sketch and took it as the standard meaning in English.
LH is the meanest airline on the planet but at least they don't have the nerve to describe things like removing +1 PC for *G as an enhancement (I guess when you're an untouchable monopoly you can afford to be a bit more forthright).