From Live Chat just now:
Normally, the travel credits are non-refundable once redeemed.
But in the light of present conditions, if the tickets and hotel are refundable, then yes, we'll return the travel credits used (or points/refund the card equivalent to the amount charged).
We want to ensure you maximize this benefit on your card, the travel credits will be valid for another year from the date they were placed back.
May I add though it may take 14 weeks for refunds due to the volume of requests received.
In the event that the refund is processed after your card is closed, then you may call our Card Services team-phone number is at the back of your card to nominate a bank account where we can transfer the amount equivalent to the travel credit/points or what was charged to card when you booked the flight/hotels.