We are an eCommerce business and sign a contract with marketing agency to manage our social media account and perform a list on service. One listed service is daily engagement that liked or comments on other posts. However, our liked list never grow and no comments engagement activities from other posts as well. The agency only be able to use employee hours sheet as prove. So we consider this is a nonperformance, breach of contract, and put payment on hold. It is the legal way to do it? Or do we have a better option?