OK in case of any future searches, here is how this was resolved

- of course this experience reminds you how far behind we are with Skywards customer services - there is NO gold line to call or indeed skywards line of any sort; in fact if you call the UK contact number as currently published on the skywards website, what do you get? Answer - a fax machine!!

- I did ring the Manchester ticket office, my past experience with these guys has been great. Result? all I got was the Indian call centre, who at one point advised me "why don't you ring the Manchester office about this?" So note to Emirates, if you are going to have overflow handling on calls, please try to think through the user experience some more.

- Anyway enough of my rambling, in the end customer services advised me there is no way to cancel with a refund waiver, excepting in bereavement or exceptional medical situation

- Hmmm, try again, so I rang back a second time, same answer.

- Again, I rang back a third time, and got a very helpful guy in customer services who said "Yes" it can be done, and here is how. Follow the regular cancellation procedure (ie. bizarre cancel-by-phone + online-refund-request-form combo), and in the Notes section of the online form, explain the situation about the accidental double booking.

- I followed this procedure, and was amazed to find that EK replied via email within two hours (!) to say the cancellation fee would indeed be waived, and a full refund processed. Now that's impressive!

So yes it can be done, and yes as usual, the patchy EK customer handling procedure must be persevered with.