Account debited twice

I purchased a box meal on the afternoon of 04 March 2015. I paid with my debit card , punched in my pin and waited. The cashier said there is a problem with the card machine and she stood around waiting for 5 minutes staring at her computer. She went to collect my order and came back asking me to give my card again and again punch in my pin. I took my food and left . Only this morning my sms's came through and to my surprise I saw I paid twice .<br> <br> Please advise how I will be refunded as I have the sms showing that I paid twice.