Tried before the month ended and they said they'll refund a purchase after they expire. I tried again on the 1st (the day it expires) because I had more expiring on the 15th so I'd try and kill two birds with one stone. First rep said that even though the previous rep said I would be able to apply the credits, he was mistaken and it was impossible. He gave me a 5$ credit for the miscommunication.
The next rep said purchase something (even now, on the 1st) and both the credits expiring today and the credits expiring on the 15th would be able to be used for a refund. I made him send an email to confirm, because I didn't want any more "miscommunications".
That purchase arrived today, and a rep was happy to refund it. All in all, I got all the credits expiring on the 1st and the 15th, plus an additional 5$.
Was it worth the time spent? I keep on telling myself no, but then here I am, doing it again.