Customers may expect perfect grammar and perfect punctuation but I've yet to find an essay company that delivers in both these respects, as well as providing good quality research. I've used seven different US essay companies (six of which were verified by another site that claims to check the companies credentials), and three different UK companies, and the writing quality varies tremendously even when the US / UK spelling differences are taken out of the equation.
Based on my experience, I think the problem is industry-wide as essay companies depend on freelance writers who need to churn out high volumes of essays to pay their bills. It's understandable that quality suffers as writers are trying to maximize the number of papers that they complete in any given period.
After trying several companies, the companies that I now return to have researchers who can at least develop a good argument based on a range of reputable / appropriate sources. It's not much of a hardship to go through the essay and make a few corrections here and there.
PS
To Devangini: There are several royal academies in England, covering the arts, humanities, sciences and engineering: only the Royal Academy of Music, the Royal Academy of Arts, and the Royal Academy of Dramatic Arts actually award degrees and none of these degrees are in "writing". The remaining royal academies house museum collections, libraries, and exhibitions; they also promote further learning in their respective areas by providing scholarships and bursaries to gifted postgraduate researchers and academics.