First, double check your service agreement with them and the notice(s) of cancellation you provided--it may be that you did not cancel your account properly and do owe them for those months.If they took the money from you--e.g. charged your credit card--after you did properly cancel and/or they had no right, under the terms of the service agreement to do so, you could sue them to recover that money. However, you probably cannot recover anything else, unless your state has a consummer fraud act or law which allows additional compensation in certain cases--and this situation meets those criteria. Either check the law of your state or repost your question with your state for a more-definitive action.If they have simply submitted a bill to you when they are not entitled to the money, but taken no other action, you may not sue yet, since you have not suffered any compensible loss. Getting an incorrect bill, if you do not pay it or are not sued over it, does not cause you any harm, and without harm or loss, there's nothing to sue over. If they do take some action against you on account of an incorrect bill, you might then have grounds to sue.