Hey,
If you are experiencing click bombing by your competitors on your adsense ads, you can do following thing..
Best way to detect the fraud clicks is to check for an unusually high number of clicks from one IP address and collect all evidence of times and unusual spikes in traffic and create a report. Google will then assess your account and examine the evidence you provide and if successful you can claim back the money you spent on fraudulent clicks. You can then use the IP Exclusion Tool in Adwords Tools (in the "Opportunities" tab) to exclude this IP address to prevent any future unwanted clicks.
Hope this helps..