smallcompany - 6:01 am on Jul 30, 2012 (gmt 0)
Google has dismissed such long ago claiming they already had sophisticated system in place.
Is there a reputable click fraud service or pay-per-click audit service
Nevertheless, if an advertiser has some doubts, G will do an investigation. here is more about all that, the link for click investigation request is at the bottom:
If your client does not accept all this what's said on that page...