Same here - after sending them constant emails they finally replied to me 3 months later. They claimed that I had fraudulently clicked the ads to gain money and that the IP address was British. So when sending the form to complain they state that they have recorded my IP address, so I asked them to compare the two addresses and they said it doesn't make a difference - I LIVE IN JAPAN! It's not like I pop over to the UK for a cuppa tea, click some ads and come straight back to Japan in a few hours. Basically it was a rival website pulling a prank and I lost quite a bit of money on it too.
Never got any ads from Google again, and I hear this happening to so many people now I just don't think it's worth doing. I've been on Amazon ads for a while and it works well but even they are now restricting some big item from getting points. A guy on my site bought a brand new Canon 5D MkIII using my links and they just never registered it. So basically I just get stuff based on books, CDs etc - you know the stuff where they don't have to pay you much!
If anyone knows a good adsense alternative I'm all ears but last time I tried a few all I got were stupid blank spaces or adverts for bloody handbags