Got a seat change email last Thursday, turns out it was a cancel and rebooked LAX for next September. Part of an EDI-LHR-LAX-TUS-DFW-LHR-EDI BA holiday.
Arrival to TUS would have been over four hours adrift so emailed BAH on Friday with copy of passport and other usual ID details on Friday. Received a reply in 28 minutes and refund available on card today.