FlyerTalk Evangelist and Ambassador: The British Airways Club
Join Date: Jun 2008
Location: Somewhere between 0 and 13,000 metres high
Programs: AF/KL Life Plat, BA GGL+GfL, ALL Diam, Hilton Diam, Marriott Gold, blablablah, etc
Posts: 33,190
You are entitled to compensation for the downgrade. This will always be dealt with by customer service afterwards and not at the airport (pretty much the same with all airlines) so you just need to go to the website and request downgrade compensation as well as delay compensation if applicable.