I've read some discussions about MEL items on this board, only to understand that a MEL seems to be somehow subjected to company policy with a certain regard of the OEM manufacturer's MEL. Still, the pilot's seat was never mentioned in these discussions.
It is clearly defined on aircraft.
Bottom line on aircraft, if the pilot's seats can not be adjusted by elec. or manual means the aircraft is grounded. I would contact your transport admin with a safety issue if in your place if your company refused to fix your seat.