Charged twice for one order!!!

UberEats has charged me twice for one order. I placed an order to pay cash because the app was not deducting the cost from my credit for some reason. I then used their support function on the app to request a change pay method. The support team said I couldn't change the pay method resulting in me paying in cash. When I logged onto the App on Sunday, I saw that they also deducted the money from my in App credits. A whole R150.74. I have tried getting a refund via their App, Facebook, email and Twitter but ultimately after giving my order number and cell number it results in silence. I cannot believe that I was ****** by such a well known organization!!!