Um, reading back through the posts here, in general you will find stories of poor customer service.
I do hope they are reading, because 1 person might be 'mistaken' however, a series of them receiving bad service over the course of many months (years, in fact) leads me to believe there are issues with their customer service or lack there of at LookSmart.
My best recommendation would be to chalk the 150 or what not up to 'experience' and concentrate your marketing dollars on companies that actively serve you the way you deserve to be treated.
There are many pay per click engines out there -> as well as other forms of traffic generation. From what I understand, the best ROI is achieved from Google Adwords & Overture Pay Per Click.
Use some tracking software so you *know* where the sales come from, and then -> concentrate on the traffic that gets the best ROI, and go from there, until you are using all the services that give you the returns that are acceptable for your business.
On the other hand, I've heard (though I don't know) they may have a customer service number @ LookSmart if you login...? Don't know if that is fact or not.
Try emailing them again & again, I've heard it takes at least a week for them to get back to you.