Ask HN: Do you take advantage of Yelp?

I just got into an argument with a pressurized wall company about removing the wall they built in my apartment. They claimed to not have a record of me calling them over a month ago to take down the wall. They then wanted me to pay $450 to remove it this week (it's supposed to be free!). I told him I would write a bad Yelp review and then he agreed to remove the wall if I didn't do that.

What do you think about taking advantage of Yelp this way?