If everything you said is stated that way in your contract, then you should be able to cancel your contract with the hospital withou penalty, but if you do, the hospital is not required to pay you for the remaining weeks of your contract. Most travel contracts allow hospitals to cancel travelers at any time for any reason (just like regular staff can be let go at any time...). I think trying to sue for that money would be a losing battle.
You need to decide if this issue is important enough to you to quit, of if you are willing to work one week of un-blocked days to get the days off you wanted. If you quit, be prepared to vacate your housing within 48 hours (if you are in company housing), and be prepared to start looking for a new assignment, and possibly a new travel company....
It sounds like the nurse manager was willing to try to re-arrange things somewhat so you could have off for the days you wanted. If that means working a few days of un-blocked shifts, that doesn't seem like that big of a deal.