UPVC Door Handles Fault?

Hi guys

Bit of a unique issue I think as I can't find anything online about this problem, but hopefully someone can help.

I'm having an issue with my front doors handles. The lock works fine but when the door is locked one handle is horizontal and the other vertical.

I'm not 100% sure as to how this happened as the first instance of this occurred when I was coming home from a night out, so my memory is a little hazy. I just know that I didn't 'force' the handle into a wrong position. It wouldn't turn the usual way to lock so I juggled it around a bit and then it went the opposite way and locked with the inside handle in a vertical position.

Has anyone had this happen to them before? Or know how to fix this?

Any help would be appreciated.