@Sarah3087
No! Don't ever refund a guest directly. You have no idea if Airbnb is going to refund them also. Always issue refunds or alterations via the Airbnb system.
Yesterday, I offered to refund a guest if she shortened her stay. She was having issues with something (that no one else is) and getting very stressed about it and I could just see this escalating. So, I said that if she wanted to find somewhere else to stay, I would be happy to refund the rest of her stay. I told her I would send an alteration, but she would not receive the monthly discount.
She wasn't happy about that. She said that I should refund her directly an exact percentage of what she had paid and do it asap.
I explained that isn't how the Airbnb payments work, she would not get her fees back that way as Airbnb take them, not me, etc. etc. Luckily, she listened and all was fine.
But, had I refunded her from my own bank account, who is to say she wouldn't have gotten a refund from Airbnb too. In my experience, once Airbnb refunds a guest, whether that was the correct decision or not, it's not easy to get your money back.