3 point door locking system jammed

[ajjbultd]

hoping someone can advise me, I have a 3 point locking mechanism on my main (aluminium) door (where you have to lift the handle to actuate before locking) but due to some reason (I suspect someone slamming the door) the handle only lifts part of the way meaning the 3 point system only comes out halfway and I am unable to lock the door!!
can anyone suggest what may be the problem and if I would be able to fix?