Explanation: If you take the 27th and do not arrive by usually 1am you are charged the one night and your resv is cxld. The reason behind this is you have reserved a site for that night and because you held it, the resort was unable to sell it to someone else. As for the 28th it sounds like at the time you called they were sold out of preferred sites for that night. This date along with Sat would be the nights the campground would most likely be sold out. But your resv for the 29th would be safe. Saying that here are some strategies that might help.
1. Call CRO again. If you can only get the 29th, take it and call back again at a later time and check for availability on the 28th. This may take several phone calls because you are basically waiting for a cancellation. The closer it gets the more calls I would make. There is a 5day cancellation policy if you want your deposit back. So keep that in mind when you are calling, persistance will pay off. You also might consider switching to a Full hook up site, there are more of those and your chances are better.
2. If you can only get your stay with several reservations, then get all your nights, have your conf #s ready and have the CRO Cm note on ALL your reservations that it is a "Continuing Reservation". This will alert the FD and RA that you you have several reservations for your stay and need to be on the same site.
3. If you have numerous reservations for your stay, fax the front desk a few days before your arrival. Include all your conf #s, dates, name and any request, such as staying on the same site for your entire stay.
I know this seems confusing and unfair but I hope this helps you get the dates you want.