The "helper" was not a professional, as expected, took way longer than estimated and then acted like he did us a favor by not charging us for extra time for it, implying he expected a fat tip to cover it and guilting us into doing so.  Only after he left did we notice the numerous scratches he left on the surface of our desk.  We thought this was a service provided by Wayfair, but seems like it's really just contracted out to anyone who shows up.  Won't use the service again.