How about keeping the receipt and submitting it to BA as out of pocket expensive because they cant be arsed to offer the service they market on their webiste. Notice the plural of meals, and the full page suggests you'll be feasting on gastronomic delights like a king...

Delicious meals and full bar service

Naturally, your World Traveller experience includes complimentary drinks and a delicious assortment of fine foods designed by world renowned chefs to keep your taste buds entertained throughout the flight:

balanced meals crafted to perfectly match the time and duration of your flight
a wide range of special meal alternatives to suit your dietary needs
complimentary bar service, hot drinks, juices and water (on some very short flights, a full bar service is not always available)

And fully described here