Replacing uPVC door only, reuse old frame?

I'm in the process of selling a house and the surveyor has told me to fix the back door, which has a blown DG unit and a knackered (corroded) handle. I think the door is welded together so I'm unable to fix either of these problems on their own.

Obviously the fastest/easiest thing to do would be to hang a new door on the old frame. Is this likely to work? Is there any standardisation? The door is probably about 15yrs old.

Ta for any thoughts on this.

The fastest and easiest thing would be fit a new DGU and replace the handles, can't believe their asking you to change the handle, its just a wear n tear part that is subject to weathering and corrosion

Thanks for the reply. It is the spindle itself that has corroded through, and I've been unable to shift it. I whacked it as hard as I dared but it wouldn't budge- either it isn't designed to come out, or it's truly corroded in place. So the handle on the outside is just dangling uselessly.
As for the DG unit, I couldn't see any way to dismantle the door to get it out (same goes for the lock mechanism)- I had assumed that the plastic was all heat welded together.
If there's a cheap/quick/easy solution I would be very happy!

Oh just for more info, the door is made by REHAU

Both the handle and the glass unit are very easy to change. You simply need to remove the glazing bead from around the glass, a strong, thin knoife should be used, ideally a strong surved blade like what is used to scrape block paving.

Then measure the glass height and width, remember to measure the thickness of the glass as it will not fit back in if you get the wrong thickness, maybe 24mm or 28mm depending on age.

Then remove the handles by the 2 screws and try to see a part number as the trickiest part is making sure the new handle will fit.