* If a Hotel has over charged your credit card for reasons that not applicable to your stay... like the $2500 charge mentioned by the OP... you can have the charge reversed the same day. The hotel GM or AGM should call the CC company and state the error and request the charge to be returned ASAP. This happens somewhat frequently and is process most GM/AGM's are familar with.... if this request is denied by the front desk agent, ask for the AGM or GM and push the issue with them.

* Don't want a huge hold on your credit card ? Put down cash as the incidental payment. No Marriott will deny you the option of putting cash down and obviously as soon as you check out that cash is right back in your hands. If you want to feel more comfortable with the cash process, spend $5 on a prepaid Visa or Mastercard (greendot network) and use the prepaid card as your incidental payment, the cash hits your card right away after you check out with no waiting time that a bank card or cc card puts you through.

* Also if it helps you any... you can always call the hotel prior to your arrival and pay for the room in advance before you arrive.