If your reservation is for the wrong room, you should consider what alternative accommodation the hotel can provide that meets your expectations. It is reasonable to expect that the room or grade of room that you booked is available.
Find out why your expected room is not available. Is it because you did not book the correct room? Check your confirmation email or letter to ensure you correctly booked. If it was your fault, then the hotel is not obliged to provide you accommodation.
If it is the hotel’s fault, you should not be left out of pocket for any additional costs that you have to incur if they cannot provide the room that you had expected.