@David-And-Barbara1 Your listing is not deceptive - it's very thoroughly described. But the guest figured out that if he didn't pay the extra charge for his real group size, he'd have you cornered once he arrived. It's a despicable behavior, but really common. Very few hosts can countenance turning away a group at check-in, knowing it could cost them their whole payout, so they back down when put on the spot. It's the same mentality as "easier to ask for forgiveness than permission."
You should have either refused entry to these guests altogether (especially if they were belligerent) or required them to accept a booking alteration and pay for all guests before you turned over the keys. You've lost most of your leverage if they're already occupying the space, but you can still insist on being present for check-out and post an honest review.
In the future, please approach every booking for 1 as a red flag. Solo travelers have no reason to book a 3-bedroom house, so in hindsight you should have asked this guest a lot more questions before accepting his request. And if you were using Instant Book, turn it off; you need to be able to vet your guests more thoroughly, knowing that Airbnb won't have your back if a disaster strikes.