Stop. Just stop. Stop complaining. Stop writing posts and tweets. Stop talking about it with your friends. Stop protesting. And stop creating ill advised petitions that have no hope reaching their desired intention. Even those who didn't give in and waste good money on this film know how terrible it is. And we all want the same thing, which is for Fox to give the rights back to Marvel and Disney so we can get a decent film out of a property that has thus far been misused to say the least.
But why? Why doesn't your voice matter in this? Because, much like the government, movie studios don't care about what you want, or even about making a good movie... they care about money. The more people try to pressure them into giving up the rights just proves to the studio that there is an audience for this product, which means there is money to be made. Now no good business man, or woman, would ever just give up on a cash grab like that. Not while they have options.
The studio already announced they are still moving forward with a sequel, much to the dismay of fans everywhere. But why not? These passionate complaints again show the studio that if they fix their mistakes, they can sell this with little to no effort. So while they use the word sequel, it can still be re-cast, and the mistakes of the first film can either be outright ignored or somehow explained away. It's happened before in comics and films, so don't be surprised if they do it again. These people aren't interested in continuity, filling plot holes, or pleasing fan boys... they only see the bottom line. And right now, they are operating under the "there's no such thing as bad press" way of thinking.
But there is a way you can help get what you and I want, and believe it not the advice comes indirectly from Disney. Let it go. Just let this entire debacle fade in to obscurity. The box office has already shown that Fox can't make money off this, don't do anything to justify them giving a second thought.
The same thing happened with Ryan Reynolds in Green Lantern. That utter debacle of a film was slated for sequels and franchising... until the fandom died down. The film was poorly received by critics and movie goers alike (sounds familiar), did less than expected at the box office (again, familiar), but the studio still pushed on for a sequel. Why? There was still a buzz, in the form of massive negative feedback. But, once the buzz went away, the franchise died.
So I'm begging you. Let it go. Let it die. Hold that anger inside, and with any luck one day, like a phoenix from the ashes, the Fantastic Four will have new life under the Marvel banner.