Rite Aid Item Exchange ATM scam, Internet

On August 31, 2012 I purchased a razor kit from a Rite Aid drug store for $10.73.  The next day  (September 1, 2012) I returned the unopened razor kit to the store with my receipt and exchanged it for a similar kit which was also the same price.  The clerk took my original receipt and gave me the 10.73 in cash and rang up the new razor kit. I paid for the new kit with the cash she gave me and got a receipt for the new kit. 

When I checked my bank account, Rite Aid had charged my account, the amount charged was 40.73.  I went to the store with the 9-1-2012 receipt; and talked to the manager who asked for the original receipt, dated 8-31-2012, which the clerk had kept.  Since the clerk kept the receipt, I am out $30.00 that evidently  the  clerk pocketed...