EU consumer rights specify many (types of) terms that are considered unfair in various common contracts, so if they're included in a standard form contract offered to consumers, they're automatically considered null and void. I.e. it's a general legal principle that because such contracts aren't negotiated, there's one-sided leverage, and certain classes of terms are inherently abusive to consumers, therefore even if a consumer "agrees" to them and signs a contract including these terms, they shall not be considered binding.
GDPR extends this concept also to consent for processing private data - there are some ways how that consent can be granted and received, but contracts of adhesion are not (will not be when GDPR comes in force) one of them. In particular, GDPR specifies that anything included in such a "take it or leave it" contract is not considered "freely given" consent and thus such a contract does not and can not give you any rights to use that data, no matter what is written there.
