I wouldn't think the LBS had anything to do with anything in this situation. They seem pretty irrelevent in this whole ordeal as they weren't mentioned till the last post and not in a way that would involve them. It is likely that when doing your servicing maybe something went on incorrectly which happens to all of us including some seasoned mechanics.

To figure out what the order of parts is you would need a diagram of the hub one of those blow out images like Shimano and others have but for your specific hub and for that you would need to know what hub it was and who made it and then reach out to that company and see if they can help otherwise I would take it to the shop and have them take a look. Generally if the shop isn't taking apart your hub as part of service you requested or because it was needed they aren't going to lose parts there because there is nothing there to lose that would have this effect unless something was done incorrectly the first time around or it is some unique situation.