Changing your flight with British Airways is as simple as contacting the company online or over the phone.
Changing Your Booking
British Airways logs every booking into an online system called Manage My Booking. Find your booking confirmation email or printed ticket, find the booking reference number and go to the Manage My Booking page. Enter the booking reference number and your last name to access your flight details and make changes to your booking. British Airways does not charge a fee for flights changed online, but you are responsible for the difference in cost of airfare. You can also call British Airways to make changes over the phone with the assistance of a representative, but this incurs an extra fee.