****ed!

I am not happy at all! Bought something at Spar on the 23rd of this month but card declined twice due to network issues and one transaction went through but was reversed. I ended up paying cash.yesterday I get notification of same transaction deducted from my account.thats fine,it happens but how come when I pull through statement the transaction with reversal doesn't show on my account where else I have bank notifications? How do I claim my money back from Spar as I have since lost the cash till slip? I want my money back! How is it possible that money goes in an out but not show on the statement ?