payment and refunds

Hi booking.com i wasent happy with that just anyone could book my listing and got a phone call late at night from some one who had payed for my aparment and was excpeting to get the keys and getting to stay over. 

im wondering how i refund payments from people that made a reseveration. and im wondering if you can refund the people because i just put my iban number on my account and it takes some time..