Had a complete, rock solid, lock up of both elevators once. Quite alarming as the column felt like it was set in concrete. It wouldn't move one millimetre, on either side. Aircraft doing big phugoids with the AP in....
The a/c had a splitter but we managed using the trimmer and eventually it all came free at about 6,000' when the ice, which was causing the jam, melted.
Diverted, as we were due to land at LCY, which seemed ambitious, but didn't tell ATC much and the pax, nothing.
Not much that anyone could do to help really.