Poor service

Service at nedbank is becoming terrible day by day. On the 24 I went to Shell garage at Constantia to out patrol when I want to pay it decline my card and show wrong pin , I then went to the ATM and withdraw cash and pay. To my surprise the decline transaction took my money when I check the balance the money was gone. I called ***** department and they confirmed that money was taken and will be returned until today money hasn't come back. I then went to garage and they said they can not give me money because they have a declined receipt. When I check my statement the transaction is not appearing but when I call nedbank they can confirm transaction. I am stuck because Shell garage are saying they can not pay back the money because they did not take and Nedbank said they can not reverse transaction but what I don't understand is that I have a receipt written decline but my money is gone