Just to complete this story, in the end CX MNL did issue the DONE4 and it was available for me to pick up at the airport, which proceeded without a hitch. Then I had to turn around and cancel the whole trip due to health reasons! I was quite concerned at how long it was going to take to get a refund, but once the tickets were couriered to CX MNL they organised the refund and it appeared on my CC statement within a couple of weeks.

Subsequently I have been in touch with them via email to organise an ACIR22 ex MNL, and that has happened quite expediently. This may be the start of a long-standing relationship...