Whilst I agree with Jonwar, having also been a locksmith for 10 years, a wide prying tool (ie: 3"+) or an airbag is unlikely to do much harm, and members of this forum are typically well above average with their problem solving and practical mechanical skills, so there's a sporting chance they'll get it open.
A locksport enthusiast is unlikely to be much help, as this isn't a lock which needs picking. I pick locks for business and recreation, but this is a quite different kettle of fish.
My advice is get your wide prying tool and/or airbag, and try to lever the door away from the frame at the extreme top and bottom (not at the same time).
This should give you a chance to peek at the locking points and see what they are. A wide tool will not do much harm to the upvc, but avoid anything which focuses force in a small area - uPVC will dent easily if you use anything narrower than 2" wide. Once you've seen the locking points, you can usually infer which was they need to move to unlock the mechanism, and with some ingenuity you can persuade them to move thusly, and open the door.
Let us know what you find, and we might be able to offer more specific advice.
A locksport enthusiast is unlikely to be much help, as this isn't a lock which needs picking. I pick locks for business and recreation, but this is a quite different kettle of fish.
My advice is get your wide prying tool and/or airbag, and try to lever the door away from the frame at the extreme top and bottom (not at the same time).
This should give you a chance to peek at the locking points and see what they are. A wide tool will not do much harm to the upvc, but avoid anything which focuses force in a small area - uPVC will dent easily if you use anything narrower than 2" wide. Once you've seen the locking points, you can usually infer which was they need to move to unlock the mechanism, and with some ingenuity you can persuade them to move thusly, and open the door.
Let us know what you find, and we might be able to offer more specific advice.