I hope you documented everything. You may want to contact the booking service for an adjustment.
Unfortunately, no one can predict acts of god such as no hot water. What you need to evaluate is the following:
* Was the replacement hotel of equal caliber? Same number of stars? Same rack rate posted on the door?
* Are you being asked to pay a differential in price? If so, you should definitely contact the booking service and notify your credit card company of the dispute.
* If all things were equal and it was a question of your not liking the decor as much, I’d probably let the incident drop and write it off to bad luck.
* Were your stay longer than two days, I would advise that people move hotels if they aren’t happy with the substitute. But, in this case, a hotel is a place to sleep and take a bath or shower with ample hot water.
* Think of the alternative. The hotel where you had been planning to stay could have registered you and you would have found out the hard (and cold) way about its lack of hot water.