I booked 5 nights with points months ago but now I have 2 credit card night certificates. I called and tried to swap out 2 nights of points with 2 nights using certificates and they said I could not. They said point nights and certificate nights come out of different inventory and there are no certificate nights available. I did check and the point night room category is sold out. Are they correct there is different inventory? I do not need a room freed up, just swapping the method of payment for the free night.