Unacceptable refund practises without informing the customer beforehand

I made a booking through Booking.com but when I received the confirmation, it wasn't what I had booked for. The confirmation email stated that I could cancel within 48hours without incurring any costs, so I cancelled immediately (within 17minutes), intending to rebook with the correct details. However Bookings.com went and deducted the FULL amount for the booked accommodation from my credit card, despite it having been cancelled within minutes. When I followed up with them, they said I would be refunded within 30 days! This is a money making **** as they do NOT warn customers that this is their practice, not even in their Terms & Conditions. This is an unacceptably long time to delay the refund for, especially since they confirmed that the accommodation had NOT been paid - the money was basically sitting with them. I now can't make a different booking as they have taken my money. I basically have to wait until after my holiday would have taken place before they refund me - if they even refund me.