Double charged for stay due to incompetence and poor systems

Hi, so I booked a stay for myself and my family online, the process seemed smooth and paid online, got the confirmation of booking, reservation number and everything. As we arrived at the hotel, we had a long wait to get to the front desk, upon checking in to my surprise I was told that the total amount due for the hotel stay was now due. I was shocked and amazed, I then showed the clerk the sms from the bank, I gave them the reservation number, I showed them print outs of receipts showing that the balance upon arrival is R0.00. The front desk then told me to pay again which was absurd, as it was already late, I was forced to pay again and was told I may be refunded if I send emails with proof. What is wrong with you people and your systems, are you dam well insane!!!! I want my money back you!!!