Account double debitted for 10 May purchase

I purchased a few items for mothers day. I was looking at my bank statement when I noticed 2 debits for the same amount for woolworths on 12 & 13 May. I knew it was for the items purchased on the 10th. I had been debited twice for the same purchase. I contacted the store and they told me I must come to the store with my bank statement and contact head office. I was very upset that I must go to the store to fix an error on Woolworths side. I emailed the manager the statement. I did recieve a call back stating it was a problem with Nedbank customers and that it would be refunded into my account on Monday (yesterday). This didnt happen and on trying to contact the store again the manger is in Durban. What is most annoying is the inconveniece of it and that if I hadnt been checking my statement I would never have known and that I have to phone and harass the manager to try get my money back. I would expect this from some ***** little shop not a Woolworths, where you go expecting quality service.