Just wondering, but how soon before flying have you been offered the deal?
I have a LHR-JFK WT+ flight in 2 weeks with the return a few days later from IAD. Do these MMB upgrades happen randomly, or is there a set time before departure that they appear?
I've booked some ET flights recently and paid the special offer upgrade price to CE for a little more comfort and tier points, bt haven't been offered anyhing on the long hauls yet