I have turned down an upgrade. Was Hilton at London Heathrow. Traveling with my sister we booked a room with 2 queens. When we were checking in they smiled and said we have upgraded you to an executive room with 1 King. I politely said thank you but that won't work. My sister and I don't want to share a bed. Took them about an hour to get us back to a 2 queen room and they apologized.