UPVC window lock repair

I have a UPVC double glazed bathroom window which hinges along the top. The locking mechanism comprises of 2 sliding locking pins in the bottom edge of the window which locate into metal slots set in the lower window frame. The handle on the window has snapped off. The windows are probably 20 years old and Ive know idea who made or installed them



Does anyone know where one can obtain replacement lock mechanisms ?