Did you try calling? I've had this happen to me, but the agent was able to see the error and fix it. Basically, the ticket ended up in a "stuck" state where it had been cancelled, but the refund flow was not triggered because of some IT bug.
(I will note the agent I got was clearly very experienced and had to try several systems to push the refund through, but they eventually managed to do it. So you might have to HUCA a few times or ask for a trainer)