Replacing a uPVC door neon rebated hinge?

Hi, the top hinge on our back door has broken causing the door to drop considerably and we have to lift it to close now, obviously this is stressing the further hinges on this side, I am about to buy a replacement hinge, i need a 13mm one, but upon trying to remove the old hinge I can't see how to remove the hinge from the frame, I can't get at the 3 screws holding it to the frame
Can anybody advise me how to remove this?
Thanks in advance
Greg