Sorry to hijack this thread. I booked WTP fares ex LHR to HKG and JFK respectively. At the time of booking, there wasn't MFU availability but I'm checking constantly to see if CW seats open up closer to the time.
Just to test the upgrade functionality via MMB when CW MFU seats open up (via Upgrade --> Upgrade with Avois, I get this error msg: "Sorry, it is not possible to change this booking on ba.com. Please call your local British Airways office to change this booking." I booked both flights on ba.com (not TA) so its strange to see this? Do I really need to phone up the call centre? Thats rather annoying...