Update
Two weeks after AZ agent told me they initiated a refund but could neither provide written confirmation nor estimate how long it'd take, I filed a dispute (small American credit union, MasterCard Debit). They said it'll be another two weeks until I get a provisional credit and the time it takes to resolve the dispute can vary widely depending on how cooperative the counterparty is (Opodo DE in my case--looks look like the charge came from them, not from AZ). Fingers crossed.