This is certainly a bit irritating but please, no need for so many

faces. It's almost Christmas. Lighten up.
I would guess first of all that you have possibly just run into an incompetant agent who can't reval a multi-sector itinerary. Did the agent have a geordie accent? Might be worth a second call just to see if somebody will reval your ticket right now or give an explanation as to why it cannot be processed.
Another possibility is that we have recently received a new version of the Amadeus system we use. We regularly receive new versions but this new one has had more than the average number of tweeks and, ahem, enhancements - primarily to go alongside the adjustments and new functions of the Fares Department. Unfortunately, this updated version of Amadeus is positively pi$$ when it comes to e-ticket revalidations and is rejecting, for no good reason, about 20% of revalidations we would normally process. I'd expect this problem to be sorted out in the next update of our systems.
Still, this is no big deal. It is just put on a queue to E-ticket Helpdesk and it is processed by them instead. If you were traveling in a matter of hours, we would still put it on the queue and your booking would just simply jump to the front as it will recognise date/time priority.
So cheer up, lets have more

faces and less of the