Originally Posted by FlyingfromAZ

I was initially booked on the LHR to JFK flight in Economy Comfort. 24hour before I did an award upgrade to business class.
When arriving to my seat in the plane, someone was already seating on my seat so we checked our boarding passes and both of us had the same seat number. The flight attendant tried to find another seat but the only available one was in economy comfort, so I was sat there and told by her to contact KL when I land for compensation.