06 Fabia Elegance Estate n/s rear seatback lock release handle broken off

I am a very old motor mechanic and I would appreciatea little guidance please. As I looks to me that a simple self tapping screw just might refix broken off plastic handle, (which has left the handle's flat base plate still in situe). Sadly there is no way to see what sort of locking mechanism is under the remaining little base plate,.. short of cutting open the upholstery! Can someone tell me what is underneath within the seat, is there anything to screw into? ..Or is the only way out to remove the whole seat back and tear it to bits??

Thanks in advance.

Keith