Had the same thing with the Holiday Inn Brent Cross London last week. Stay there quite a bit and called up to secure my regular upgrade to an Executive room and was told I would be upgraded to a Superior room. (Guess what...no superior room bookable! Just standard & exec)

When I told him that there was no such thing as a superior room in that hotel and that it wasnt bookable he told me that the superior rooms are not bookable online (yeah rightttttt) In the end got the executive room but it was funny to hear him trying it on!