CSR stands for Customer Service Representative. Large companies have them. That is who is called when customers show up unexpectedly.
Smaller companies either have sales or marketing, or if really small upper management would handle it.
When a customer shows up with out an appointment it is either a cause for celebration or trouble.
You don't call the cops (unless you have something to hide).
You find out why the person came all that way (writing an article, research for lawsuit, going postal, etc).
You are confusing BFL with a retail business, they are a hardware design firm that just happens to sell to end users. Dealing with people who just show up as a small business is one of the most annoying/time consuming things to deal with on the customer side when you are not in physical retail, independent if you tell them to fuck off or try to meet their requests.
Look at it this way, if you refuse every customer who doesn't make an appointment what will happen?. They will make one if it is important enough. If you rather try to service every damn person who shows up unannounced at your door, you are gonna end up in a situation where the general census becomes that you get better customer service if you walk up to their door and annoy them.
Unless you are brick and mortar there is no benefit of wasting customer service resources on this for "normal customers" when they can't even show the courtesy of making a appointment. It just creates expectations you can't control when you let your customers decide the terms rather than setting them yourself. Sure if Joe with trousers of gold who is 10% of your total business knocks on the door it's a different matter.
But I guess in the US the customer is always right and if you are not satisfied you can always sue for just about anything.
There is a problem in your logic, first it is anti-social/anti-customer. Second, the whole idea of having a customer is to sell something, if there is a problem...you actually have to deal with it. If you need to pay a former walmart employee or greeter then do so if it meets the demands of customers. BFL is loaded to the gills with pre-order money. A grand less a month is no big deal.
Third, If you complain, you usually do get prompt customer service. There is no difference between doing it on an email or over the phone, or live in person if your response will always be the same. Which in the case of BFL it apparently is.
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Finally, if you sue BFL, you usually have a legitimate reason for that. It usually means you have a case behind it.
The guy who visited implied he has several Mini-Rig orders with one or more purchasing partners. It would imply he has a right to tap on their front glass at their offices to get answers....which he unfortunately got none....with the exception of a bad impression of a situation.
The man who visited also mentioned that those partners are clearly worried about their purchase and may pull the plug on it. Which means it would be extremely reasonable to try to assure those partners with a visit @ BFL offices. Which of course, didn't give him a positive impression.
As far as I can see, to make an appointment you'd need to contact BFL. Consider their email response times are now half a month in some cases. Who here can plan out with good accuracy whether they will or will not be in the neighborhood in a month? Schedules are tricky things...especially if he is from out of town. (which I assume he was)