Glass cutting

I have a full height mirror which I need to cut down by about 10cm. It didn't fit in our lift so we had to carry it up up 5 flights of stairs; therefore I would quite like it to be done in situ!

Can anyone recommend a glazier who might be able to do this?

Thanks

It's not difficult to do it yourself, with a metal straight edge, and a decent cutter. Score once slowly and accurately, then keep scoring, deepening the original
Then a sharp tap, or lay it on a hard floor, with a pencil at either end of the score line, running under the score line then push down on the excess piece.
Dress it with wet-and-dry paper from a car shop, or a knife sharpening stone.

Do be careful though. If it is made of toughened glass it will not cut; it will just break up into chips.