walmart money card theft of money, Internet

When you got your gas you used the "Pay at the Pump".

What most likely happened is that when you used your card the pump automatically holds a certain amount of money.  This is generally in the $50-$75 range(although I have heard of some going as high as $125).  This is done because they do not know how much you are going to pump, you would actually have found if you kept pumping it would have shut off at this amount.  Normally when the real debit goes through this hold gets removed, but this does not always happen.  In this case you will have to wait until the hold "falls off",  which depending on the bank may be anywhere from 3 to 14 days.  You may be able to talk to the Gas Station and have them remove it, but generally these people don't know how to request this from their merchant processing company.

Now, the only reason I say this is most likely what happened is because if you only had the $29 charge, having them hold almost $300 is something I have not heard of.  Have you gone on-line to look at what debits have been put on your card?

One more thing about the holds at a Gas Station.  If you don't want this to happen again you need to go inside and request a specific amount.  And this goes for any debit card not just your Walmart card.