Originally Posted by
Ldnn1
But it also seems clear that this was (a) not the flight OP booked, nor (b) the replacement flight that BA MMB showed him as booked on.
BA, as the ticket issuer, has to take responsibility for this miscommunication / system failure.
The question is "compensation" not whether BA rendered exemplary customer service.
EC 261/2004 applies to the operating carrier, e.g. US.
If BA feels up to it, it may choose to toss OP some avios or other gesture.
For what it is worth, nobody should ever rely on anything other than the records of the operating carrier. Period.