Is there a software which shuts down the Internet connection when a given limit has been reached?

We are in Moscow, Russia and we have an office in a business center. We have a simple windows internet sharing in the office. Our internet provider is the business center itself. And they are buying the service from a telecom company. I do not know whether they are buying a limited or unlimited bandwith. Whatever it is, they are selling this connection to us as 50$ per 1 GB (upload+download). We have no other chance to buy another service. We are proctecting all our computers with updated AV programs we have automatic updates for windows on. Any virus or worm possiblity is almost zero. However, the business center IT staff told us that we have used a 22GB bandwith within this month. We think that this is impossible as we pay a lot of attention to downloads because of this high price per MB. So in any case, we need to limit our internet connection when a daily limit for example 100 MB has been reached.

You can purchase some higher end routing equipment that can do just that. The best solution for you in the short term is this one: http://www.netlimiter.com/

Should do the trick!

Well try this program: Shutdown Expert at http://www.zylsoft.com/shutdown.htm
It can shut down software/PC and I think hardware too on the time that you put. You can shutdown the Internet start up software depending on your router. good luck!