Again, your making it worse bud. Just flag fake reviews to google, make your statement and move on. Focusing in on this makes it worse.

In a retail environment there will ALWAYS be dick heads that will try to mess with you. I get its stressful and looks like it's over but just move past it and it'll get better.

End of the day, just respond to complaints like the threat the guy gave you with a business like manner, a simple "Sorry store credit won't suffice, we will process a refund processing time for refund will be x amount of time" hell there are even restocking fees or processing charges that you may not need to refund (I've had retailers not refund me CC processing fees on refunds).