Hello @Stephen1604
If this guest never set foot in your place and cancelled before his check in date, he should not be able to leave a comment. You can contact CS and get this review removed. That will at least get one 3 star review removed!
Unfortunately, Airbnb do not seek average, they seek excellence and extra-ordinary and they consider a 4* review as not good so if you are getting too many 3* then yes, you will get an automated message saying that you risk having your listing suspended.
Are there any areas in the review system that you could maybe improve upon, cleanliness, check-in procedure etc?
All the best
Joëlle