Can I rebook a flight made with a Barclays upgrade voucher?

[kynazanatoly]

I’m planning to book a return flight on a high-demand date of a high-demand route using the Barclays upgrade voucher, with an outgoing flight on day A and the incoming flight on day B.

My plan is to do the following:
1. On day A – 356, get a flight leaving on day A and returning on day A + 1.
2. On day B – 355, change the return leg of this flight to be to day B.

I’m aware that I can cancel flights and keep the voucher, but that would mean someone could snatch my outgoing flight on day A.

Can I just change the return leg of the booking without having to cancel and rebook?

[duggie1982]

I have an active booking with BC upgrade voucher and it will not let me change it online, says i have to call

[kynazanatoly]

If you do change it, can you confirm whether you can change it by calling?