@Ronnie108 I agree -there is no reason why a guest should have to wait 3-5 business days for a refund with today's technology for a clear cut case.
I had a guest who, immediately after she booked, noticed that she was charged double what she should have been, messaged me to see if she had misread the pricing. I assured her that she hadn't, that I had also seen immediately that my prospective payout for her booking was wrong, had already alerted Airbnb, and that she needed to as well.
She did, they admitted it was a tech glitch, and that many guests had been overcharged that day. That she would receive a refund for the overcharge within 15 days! It was their error- it should have been credited back immediately.
When something similar once happened to me with an airline ticket, that they had added a charge they shouldn't have, the credit appeared on my credit card account within an hour after talking to their customer service dept.