Quick question please. I have flights in J next week booked with Avios as straightforward redemptions. I need to change to the previous day, and there is only F available. So I need to change date and class, which I presume means refunding my flights and then rebooking in F. I have tried to call but can't get through. If I cancel and refund to a voucher, can I use this immediately to book the flights in F? Obviously there will be more Avios involved to book in F so can I use the voucher as part-payment? Or any suggestions which don't involve calling?