Offer and acceptance requires a 'mirror image rule' to be satisfied, meaning an offer is made and the acceptance matches the offer directly, resulting in a consensus ad idem- a meeting of minds.
Ways to avoid the rule on privity: the contracts act 1999: s1(1)- a person may enforce a term of a contract if they are explicitly stated as receiving a benefit from the contract, s1(2)- also states that the parties must intend for the term to be enforced by said third party.