Cancelling a booking and then re-booking to go from WT to WTP for an extra £200
I have a flight out to the States on Monday - booked a week ago, and it is fully refundable, just checked the web - and I could re-book to travel in WTP (currently booked in WT all the way) for only £200 more - if I do this - could I call up and just pay the difference or would it be a refund and then another booking?
Note I cannot do it online, as it is a 4 leg trip - first and last sectors on BA - middle two on American.
Thanks,
AAF