Did you buy it from a Nissan dealership? If so, I would demand to see the results of the 3 or 4 battery tests that your Leaf should have had, and see how many bars it showed after each test. There is another thread on this site about a woman who bought a Leaf that had the BMS reset:
http://www.mynissanleaf.com/viewtopic.php?f=4&t=18539" onclick="window.open(this.href);return false;
By following the paperwork trail she was able to prove that the dealership had reset the BMS, but I don't believe she had to pursue litigation because she also lost the 9th bar and qualified for a new Lizard battery, installed by a different dealer IIRC.
https://www.facebook.com/groups/seattlenissanleaf/permalink/882097691821669/?comment_id=882314801799958&offset=0&total_comments=17" onclick="window.open(this.href);return false;