You are the Project Manager on a project where a seller is not performing in accordance with the contract. Specifically the products delivered by the seller so far do not meet the acceptance testing requirements described in the contract. To make matters worse, despite negotiations, the seller is refusing to admit that it has a problem or to correct the issues. Your procurement is at a standstill. Explain your some of your available options under the UCC before you have to resort to litigation or ADR.