Charged for booking when states FREE booking and cancelletion before 27th Nov 2017

I have been charged a MASSIVE 50% deposit off my credit card for Glory Bush apartments in Margate after booking.com CLEARLY stated it was free reservation, pay when you arrive, as well as FREE cancellation before the 27th Nov 2017. I cancelled immediately and now my bank tells me I have to pay a charge to try to recover the money!! @StandardBank way to look after your customers! I WILL NEVER USE BOOKING.COM AGAIN!