If it was a USA-UK booking, paid for in dollars, then that's typically a US booking, but a few more specific details about the booking would be helpful.

Perhaps you coudl ask BAEC for the fare basis on the booking, and we'd also need the date of booking. Then we can look up the information. If it was a UK agent you spoke to here, it's quite possible they didn't understand the credit note arrangement, if that applies.