I don't know about the USA, but the idea that anyone can deny you from resorting to a court is not just astonishing, but fundamentally wrong, a denial of a basic civil right. It is attempting to put the company above courts and justice - like contempt of court. Even the Prime Minister would be rapped for that.
One of the bases of civilisation surely is the ability to ask peers and/or "elders" to intervene in a dispute. It is for them to decide it there is any case to answer. That trumps anything else written or spoken.
I would expect a UK court to brush aside any such nonsense with hardly a comment, whether previously "agreed" by the parties or not. This is made more explicit by the concept of "unfair clauses" in contracts.
Unsolved mysteries of the Universe, No 13 :-
How many remakes of Anna Karenina does the World need?