You can't avoid screening potential service providers yourself. Get some leads from local sources and then check them out, choose one that seems to be a good fit. Their ads, comments from other customers (if you talk to any) and their portfolios are what you use to tell if they are likely to meet your requirements.

You may have to engage more than one business to get everything you want, the way you want. Followup guidance, for instance may have to come from a second party calling themselves a garden coach. There is a tendency for installations to be handled by one set of contractors and maintenance to be the specialty of another, a maintenance person might be who ends up helping you learn how to keep the garden going. Many designers do that only, others have design and build companies. In addition to variations between specialties different approaches are forced by market trends, for instance many contractors are doing mostly maintenance at this time because new installation jobs are scarce.