I booked a flight with a voucher and now I would like to change that flight to a day earlier and that flight is $20 more. I didn’t see a way to pay the extra $20 with the money still left on the OG voucher. If I was to cancel the 1st flight and rebook on the new flight, will the money from the 1st flight go back on the OG voucher or will I be issued a 2nd voucher and if so, will I be able to book the new flight with 2 vouchers?