Your relationship with the booking agent is most likely spelled out in the contract, or Terms and Conditions, to which you agreed when you made the arrangements.
Oh - you didn't read those? That contract describes the rights that each party has, and, since we know nothing of them, we really can't help in any specific way.
Personally, I think they screwed you. In a big way. If they do not restore your original accommodations, then you can try to keep escalating the problem up the supervisor ladder - if possible. Some places make it very difficult to speak to the next level up of management.
There is probably some consumer board with whom you can file a complaint.
One technique that has been used by people when fighting a non-responsive company is top use the internet and social media to make a big stink about it (facebook, twitter and so on - hint: ask a 14 year old about them; they know more than most adults do). Some people create a website that details the problem, their efforts to resolve it and the lack of any satisfactory response from the company. If enough people catch on to the problem, companies have been known to actually solve the problem rather than get continuous bad publicity.