How can I report a problematic store on Shopify?

I’d like to know also, I made a purchase for a decent amount of money to Livatro, and now I don’t get answers to my emails, and the product hasn’t been shipped. What are the Shopify assurances that the companies they host are not scams? What support do Shopify gives the customers to make them trust in the stores they Hosts? And how does someone simply get in touch with Shopify to report a store that is in default of their contract agreement?