All they can do is hold your $1,200 of security deposit that why a lot of tenants do not pay last month rent and let them keep the security deposit. You can demand a itemized bill and take them to small claims but you may lose

If you did not pay last month's rent or already got your deposit back. The landlord can sue in small claims court but they have to sue at you new address unless your still in the same city/town as the old apt., Note in some states its the county.