I have similiar situation with Booking.com. On May 23, I reserved hotel in DC through booking.com, and 5 min later I called booking.com to ask if hotel let us 2 adults and 3 kids live in one room, booking.com checked hotel and told me hotel can not let us in one room, so booking.com customer service said he can cancelle the reserve free of charge since it is within 24h and so he cancelled and email me confirmation number too 5 min later. However hotel refuse to refund the charge and hotel said there is zero second free cancellation. we have to pay it even we will not go to that hotel. I called booking.com many times and every times booking.com confirmed me I will get refund. Finally I could not get refund, and foutunately booking.com refund me totally since I have all the email that booking.com claims I will get 100% refund. I finally get refund from booking.com after one month later and booking.com said they will bill to hotel and let hotel pay the charge. also I got additional 25 euro for "good will" money from booking.com.
I think hotel and booking have different policy. you need talk to booking.com.
