My brother just missed his CX flight (he used BA miles for the CX award ticket). When he tries to change to a next day flight, BA said if the passenger doesn't call within 24 hours to cancel or change, the ticket is cancelled and all the miles will be lost. The BA rep said it is in the fare rules and nothing can be done. They said the only thing they will refund are the taxes minus the $75 cancellation fees. Is it true ?