From BA.com
Can I change my BA Miles booking once it has been made?
Answer
You may make a date or time change to any British Airways sector of your itinerary free of charge, up to 24 hours before departure of your first sector.
Once your journey has commenced, changes cannot be made to any subsequent flights in your itinerary.
Please note:
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Changes cannot be made to partner flights, at any time.
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If you wish to change your departure or arrival airport, you must cancel your existing booking and make a new one.
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If you cancel your existing booking outside 24 hours, your BA Miles and taxes will be refunded, less an administration charge.
Please also note:You will only receive a refund of your BA Miles if your entire itinerary is with British Airways.
If your itinerary is solely or includes any partner flights, your BA Miles will be forfeited if the booking is cancelled at any time.
Cancellations within 24 hours will result in a loss of BA Miles paid for that journey.
If you wish to change your BA Miles booking, please contact your dedicated Service Centre.
Their telephone number can be found if you click here.
As per clause 14.1 of the Executive Club Terms and Conditions, name changes are not permitted.