This appears to be be a business dispute rather than a phone scam.  It appears he didn't call you, and it also appears that your "friend" doesn't have a clue as to how real estate transactions occur.  Once the house is bought, that is the owner.  Unless your "friend" had executed a lease agreement prior to sale, I would have to say that him staying in the house was akin to trespassing.  This site isn't Yelp.  If you want to give someone a bad review, I suggest you go to sites designed for that.  I would also suggest that you take the time to read the homepage which clearly tells you what this site is for, and also the TOS.  I have reported your post and depending on what the mods think, it may come down.