Fitting a upvc door requires quite a high skill level. If not fitted correctly they wont open and close properly. There is not a lot of strength in the upvc door sash, even with the internal reinforcing within the extrusion, so you may need to toe and heel the glass to get the door sash square in its frame. This is not answering your question but you should research "how to install a upvc door" before you rip your old frame out.
Now to your Q.
Quite often a door is deliberately under measured in its width to allow for installation obstructions such as thick and tall skirting, pipes, etc that would otherwise obstruct the door from opening. So extrusion manufacturers make add on profiles of various thickness's for that reason. These add on profiles simple click onto the outside of the door frame profile to make up the difference. We actually used to automatically add a 20mm add on to the hinge jamb of all our upvc doors to make sure we allowed adequate hinge to plaster clearance.
If you knew the profile manufacturer of the door you have got you could locate the correct add ons, but I doubt you do?
You could pop into a local window manufacturer and see if they have any add ons that will suit, even if not an exact match you could possibly self tap screw them on.
Alternatively add some flat upvc trim to the jambs. your only talking 25mm to make up overall. I am thinking one piece of 10mm thick flat trim to each side. (I do not know of any pvc trim at 12.5 mm). You will be left with a 5mm difference, but you may need this 5mm to allow you to square and plumb up the door, if you looked into "how to install a door" you will know why you have to square and plumb it up.
When you have secured the frame with frame fixings (and pack tight where you fix or the frame will be loose, but not too tight so as to bow the jamb inward or you wont close or lock the door properly) use expanding foam to fill any void.
Finish off with a "D section" trim down both sides glued to the face of the door jambs to the brickwork as an architrave, this will conceal your 10mm packers at each side.
