The first half of your post makes some good points. It's wise to stick with a company located in the US, UK, Ireland, South Africa, etc.; these are countries where English is the native language. Customers should make sure essay companies have an actual business address that matches the name of the site. If you contact the company, you should be able to speak to someone who speaks English in a native accent using native idioms. You want an essay written in English, right? Why would you source it to a company whose customer service and sales reps can't speak English well?
Try this: "I'm sorry; is there someone there whose English is better than yours? No offense, but I don't understand you very well, and I'd like to talk to someone else who speaks better English." If they can't find anyone, or try to put you off, those are red flags.
Regarding the second half of your post, you have to realize that this is not a place that was meant for recommending specific sites and services. People here tend to be skittish about the commercial motives of others, because there is a lot of spam and poaching that goes on. I know that with certain people this seems like an advertising space, but there are plenty of places like Essaychat to look for specialties and boost specific services. If you ask a legit company for a specialty, generally, they will either find someone or tell you that they don't have anyone who can match it.