HELP - Monthly Bandwidth Transfer overload

Does anyone can help me with my site?  It is "under maintenance" for over 2 month, But even then some bots are accessing it and cause Bandwidith to overload and the site goes off line.  
 

If you can see the IPs, then you can find where they are coming from. Once you know that you can block them from your site in your server panel or htaccess file. If you find it coming from a particular country that you feel you can block, then you can block the whole country. This is a part list of my htaccess and how it looks:

<Files 403.shtml>

order allow,deny
allow from all
</Files>

deny from 91.198.94.xxx
deny from 112.119.21.xxx
deny from 1.0.1.0 - 1.0.3.255
deny from 1.0.8.0 - 1.0.15.255
deny from 1.0.32.0 - 1.0.63.255
deny from 1.1.0.0 - 1.1.0.255

Hope that helps, Search Google for IP Lookup, Then search for IP Country Block. for the list of IPs for that particular country. If that is the route you take. If they are hitting a particular file that maybe a different issue. Make sure your passwords are changed frequently or secure.

There is no way to stop bad bots from crawling a site using a robots.txt file, they ignore them.

Blacklists just grow and grow and grow, and grow.  Read up on whitelists.    The port for website traffic has to be open, otherwise no one can see your site.

If you are running Apache, you can put a .htaccess file in place and do a deny from all, allow from your whitelist.  You can whitelist such bots as googlebot using the user-agent; however, the bad bots are faking the user-agent.  See this article: http://rubereality.com/2012/03/01/whitelisting-googlebot-and-others/

The bad news is that bad bots can be from any country, and they are constantly changing IP addresses.  Just block them all and allow the bots you want.  I suppose you want Google and Bing to crawl your site; so you want to allow them.  Whitelist are much easier to manage.