There is an interesting story in a Cre8asite Forum thread about an AdWords customer who was able to get a rare "courtesy credit" from Google.
To make a long story short, the 10 year old AdWords had some maintenance done to it by the advertiser. When the advertiser added some negative keywords, the default switch to target worldwide versus the very strict regions the campaign was originally set to, was flipped. So the campaign started to show ads everywhere, as opposed to the specific regions originally set up.
So the advertiser saw his account being charged for massive amounts of clicks.
The interesting part was Google did give the customer a credit, they called it a "Courtesy Credit" and not a refund. They also said it would be a one time thing.
The advertiser finds it to be deceptive, saying turning on defaults when modifying campaigns, even when the defaults were originally set the other way, is deceptive. He believes that is why Google's clicks on ads increase quarter to quarter, because Google is confusing advertisers into buying more clicks with hidden defaults.
I recommend you read the thread carefully, if you do any AdWords buys. You don't want to be in a position of asking for credits.
Forum discussion at Cre8asite Forum.
