Double charge on credit card

We had dinner at The Black Swan on 21 May 2015. Paid by Credit card R528-00 including a R60-00 tip. Realized the next day that the exact amount has gone through twice on my account with two different authorization numbers. My bank says this makes it legitimate purchases and I have to sort out with the restaurant. I have spoken to manager on duty Yolande twice, giving all the details, but no positive response.