Hi Sanjay, I have heard good things about City Rain--they have a lot of great reviews on Fresh Chalk. Also, Aquasense might be able to help. Hope this helps!
In an emergency you can probably shutoff the water in your valve box (the plastic box in the ground). You will definitely need an irrigation person to work on it. I like City Rain personally, but they tend to be busy and somewhat hesitant to take on more customers. You might try calling them since this is the off season and they don't really get rolling until May/June.