I had a credit also, and because I can’t phone, it posted a problem. However, I booked a flight I wanted on the website and immediately contacted AC Altitude Twitter team and they replicated the booking with the credit applied and did all the change fee charges and cancellations to the same credit card. Having the “live” payment transaction in the system I guess got around the problem of not being able to handle payments over Twitter.
I had to reclaim my preferred seat via the app. There were some bumps with that as I seemed to be occupying two seats at once but eventually seemed to be fixed.
It would be so much simpler and more accessible if they could just generate an eCoupon for the net amount of the canceled service less the change fee, but it seems they not only process those separately but also the tax added and tax refunded.
I’m not counting my chickens until I’m on the aircraft in my selected seat but so far so good.