>>> $500. security charge...
Was this a charge or a deposit?
You said you were on your honeymoon. Were you under 25? Rental companies sometimes require an advance deposit (not a surcharge) for drivers under 25, or drivers who decline the insurance and waiver programs, or for renters who plan to pay cash, or renters who use debit/check cards.
Did they refuse to give you a car or did you, thinking this was a surprise real surcharge, cancel the reservation at the counter first? Remember, if you have a reservation including a Priceline or Hotwire reservation, they must give you the car for the agreed upon rate plus taxes that everybody pays plus deposits mentioned in the reservation or Priceline, etc. agreement, or you are entitled to your money back with no charge for driving you back to the airport.
You really do need more credit limit or more than one credit card for use while traveling, to cover things like this. In a few cases it is not a real charge but it freezes part of your credit line so a credit card with a low credit line won't work elsewhere. In a few cases the hotel or car rental agency freezes too much just becayse they made a typo.
Next time a company makes a charge they promise to refund, have the company run the credit machine to make the credit slip to hand to you before you leave.
Disney hints:
http://members.aol.com/ajaynejr/disney.htm