Why has Comcast increased the cost of my service by over 50%?

Comcast has increased my cable bill by over 50%! There must be a law against this. on over 15 of my current stations, I receive a message that states "We have enhanced our network to bring you more features," but when I call the number, I'm told I must pay an additional 40 dollars per month to receive the same channels I already receive! This is a rip-off and I'd like to know if anyone has filed a lawsuit.