Those in the US. Contact your local representatives and tell them that in exchange for your vote that they should support Bill 401 and 987.
This should be the top post everywhere!
Petitions are great at raising awareness to an issue, but ultimately they won't change anything by themselves, and can be safely ignored by large enough entities like the payment processors.
The only real way you can stop their abuse of power, is through legislative changes. And those bills are directly targeting this problem.