Any honest SEO agency should be more than happy to talk on the phone to you
, and to explain what they will do for you IN ADVANCE of you parting with any money. Most people wouldn't something like business insurance without knowing what the policy covers, treat SEO agencies the same make them work for your contract, and ask lots of questions about what they will do to promote your website, and in what ways their work is ethical'. If they don't like you asking these questions, walk away and find one that is more helpful.