Edit: Amazon is also relevant due to their Android app store and soon in-app purchasing. I expect them to start an ad network for apps too.
I'm sure Amazon spends way more money in keeping their customers happy. They seem to realize this is good for repeat business.
They make it pretty hard to initiate what should be a completely hands-off (for them) error report too.
For example on Google Shopping they virtually always lie about the purchase price for goods that you find, then the top listed suppliers also lie about the price too. There's no [simple, visible or accessible] way to report either situation.
From Google's POV this should be an automated system. Once complaints breach n then check that the listed lowest price equals the "best" price of those listed by suppliers. If not then correct the lowest price returned for that query.
If complaints for a retailers price for a good breach m then scrape the on-page price (preferably using an anonymous IP) and compare with the retailers reported price on G Shopping. If there is a difference correct the difference, admonish the retailer and decrease the retailers reputation score. When reputation score is below x remove the retailer and send them a "naughty-naughty" letter.
Why the advertising standards/trading standards people aren't issuing massive fines to Google and their associates for false advertising in this way I'm not sure.
Then again, have you had more success interacting with Google when running ad campaigns?