Unopening UPVC door

Assess where the bolt is positioned through the frame of the door from the inside. Drill a 5mm dia hole near the bottom edge of the door frame and elongate sideways to expose the bar that drops into the frame base Using a lever (Screwdriver?) lever the rod upward at the same time as twisting the handle to allow the mechanism to unlock the door.

Either the bottom bolt is misaligned or the locking mechanism inside the frame is broken. If you can't remove the hinges then the only way I know of to get at the locking mechanism is to take the sealed unit out and cut through the frame if the locking mechanism isn't visible. If you know who installed the door, and they are still installing your model, they might be able to get replacement parts. If not, you will need to call a replacement window/door repair firm. If they can't fix it then you will probably need to get a new door and frame.

Had exactly same problem with my father-in-laws patio door............ managed to open it by removing the glass unit which then allows you to twist the door and lever it upwards to free the caught latch. Turns out the bar that operates the lower catches had detached from the handle. Once the glass is out and you spring the door out a bit, you might also be able to get a knife in the gap and force upwards one of the pins that are attached to the detached locking bar.

Geoff