Booking.com deduct money without consent and NO refund

On the 27th of August I made a reservation whereby (1) payment was only due on arrival and it offered (2) FREE cancelation. The FULL payment was deducted from my account on the 27th of August, unexpectedly. As per the cancelation policy, I canceled the booking on the 10th of September as our plans changed. TO DATE I have not received my refund even though the website confirmed to expect it within 7 days. The hotel, Casa Boma Lisboa claims they did not deduct the money and that it's Booking.com and Booking.com is not giving me any feedback on this. I received a no-reply email to send proof of payment to the follow up email from them, which I am still waiting for. Contacting Booking.com is impossible and you get absolutely nowhere reporting these issues! Pathetic!!!