I was hoping to pay and reserve extra legroom seats in advance of our flight from LHR to KUL in June but received the following response from MAS:

"We regret to inform you that we are unable to book you the seat with extra leg room (Emergency Seat) due to safety reasons. Emergency seat can only be requested upon check-in at the airport."

There are some remaining emergency exit seats are available for purchase when I create a dummy booking (£35 each way, I think). Some are already occupied.

Is it really not possible to reserve in advance?