Refund Of A Deposit

I have been in washington and checked in Marriott washington dulles airport, they charged my Visa Electron debit card with $25. Once I checked out, the lady told me that I have to check my account within 3 to 5 working days to have the $25 back and till now the amount is still pending in my account. I called the hotel and they told me that they didn't use the $25 and there was no transaction done. Why the amount is still on hold in my account and what should I do to have the $25 back to my card ?