what in the law protects us from those who would take advantage of contract law to ruin someone without them knowing about it before it''s too late

due to the fact that there is no law enforcing anyone to have to read a contract, and that in a contract it''s maker can write that it has the authority to change it''s rules"at any time, and without prior notice to you", like for using software of any kind, in the case that they try to take adcantage of that and modify it so that because anyone was using their services one day now has to do something "whatever" that the users will not like, but them that made the contract did not have to inform them about it, but they did not have to be warned,, is there a law that prevents the way contract law works from giving anyone the advantage to ruin anybody like in this example?