if it`s just the handle thats snapped then it`s a case of un-doing the screws and replacing the handles. google (upvc door handles) and a number of sites will explain how to measure your handle so that you get the right one.
however if the spindle aperture in the door itself is just spinning then you need a new central gear-box. if this is the case then you will need to remove the lock-strip (locking mechanism) from your door!
i have done this for a customer before and i had to de-glaze the door, cut the hinges, jiggle the door out, remove the lock-strip to find out what one was needed and order it, fit new hinges (which i ordered before hand), re-glaze and fit a sash jammer so the door could not be opened whilst waiting for the new gear-box to arrive!
weigh-up the costs and hopefully it`s just your handle
levilewy
April 2010