I am not seeing where there was an email modifying the 12 month lease. Other than possibly the prior manager remember that you had spoken with him/her about a shorter lease term. As it stands, it seems like you are bound by the contract you have signed. The written contract will trump the oral agreement, unless you can come up with proof that a mistake was make in relation to the lease term. Proof will have to be more than "I said, manager said". I suggest working with them to find a mutual resolution... Maybe you offer to find someone to take over for the last 3 months. Or offer to pay them the 10th month in exchange for a release.
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