While I have some sympathy with the OPs position (as in Mrs TT1F has been known, in the past, to make her problem my problem and then red-phone me), it does appear that making yourself unavailable to take calls when needing to change a flight in your name could appear suspicious at the very least to the reservations agent.

In this case, BA stuck (rightly) to the rules and your OH acted unreasonably IMHO. Whether you choose to pass my nugget of insight on to her is, of course, another matter..