In reply to BikeClimbWalk:
First and foremost, anyone attempting to rescue a stuck, scared or non cooperative climber should only do so if they have been suitably trained to do so. Secondly in most indoor situations this will only be wall staff, who hold a relevant qualification i.e Cwa.
There are many publications available on the subject of rescue, many of which take a lot of time to read, and most of what they teach do not take into account all of the variables and scenarios that can occur at your local wall...
Thirdly anyone who thinks they are doing the right thing, carrying out a "rescue" had better be absolutely sure that they have exhausted all possible simple ground techniques before ascending to give help. There are many very simple and effective ones that can be used with climbers who might become "stuck"' without having to put you at risk ... As it's already been mentioned..... Lower them off, tell them to climb down if they won't sit down in their harness, or better still attach a spare tag line to the rear of there harness to give a little downward assistance with out you having to leave the ground.
If you are considering self belaying with a gri gri, be warned........back up the down side of the rope with overhand knots in case they panic and pull your gri gri handle, whilst you try to help them !!!