UPVC door won't shut?

My UPVC door won't shut. You have to hold shut and pull up the handle to shut it. It no longer automatically locks from the outside, you can just pull handle down from outside to get in. The only way to lock the door is to push the door to and lock it then, without pulling handle up. It isn't properly shut, only being held by the lock. I'm not sure if the door has dropped slightly as it seems to be catching on the bottom.