Are all UPVC patio sliding doors height adjustable?

Ours is about 12 years old. It has 8 latching points, 6 are on the side and the other 2 are at the top and bottom where the locking bolt goes up and down. It often catches on the bottom bolt plate when the weather gets really cold.
I thought I would take a look at it to see if I could raise it by a few mm so that it cleared the bottom place but I cannot see any height adjustment screws. The only screws that I can see are for holding the lock mechanism in place. I cant see any holes along the bottom edge (face) of the frame either (inside or out).

Do some doors need to be removed for the height to be adjusted?

It also seems slightly different to all the doors that I can when I have been "Googling" in that the sliding door is on the outside of the house. All of the ones that I have seen have the sliding door on the inside. Maybe I havent looked at enough examples!

Thanks

Alan