Can I use a Sharkbite on a running pressurized pipe?
Assuming this is inside your house, don't even think about it unless you are prepared to clean up the mess from water a couple of inches deep on the floor (and getting into the rest of the house under the doors, etc), and spray all over the walls.

If you have never tried this before, expect the jet of water to knock things out of your hands, so the job takes even longer while you are wading around in the flood trying to retrieve them!

You don't say what country you are in, but in the UK you should be able to find the shut-off valve on the curb and close it yourself. It's not clear why you need a contractor to do it for you.