Make sure that the "special room" is in the category of room you reserved - for example if you reserve the cheapest room on Expedia but want the hotel's best view don't be surprised if the request isn't honored. Then, email the hotel and ask for the email address of the reservation manager, or even better of the Director of Sales or the Front Office Manager. If you email the request to a specific individual and if it is reasonable, you have a better chance that the request will be acted on.