NY is hard to moniter month by month, but they have a savings guarantee over '12' months, meaning you must stay with them for 12 months for them to refund you if they weren't at least 1% cheaper. Shreknit, your above '6' month example, even if proven to be true, doesnt qualify for the savings GUARANTEE.
In NJ their 12 month fixed plan is 100% cheaper than jcp&l by around 15%, and you wont find anyone to dispute that.