Comparison: EssayBox vs. RoyalEssays. Which is better for UK students?

[SalmaWillis]

I'm helping my cousin (who's an undergrad in London) find a reliable service for her final year project. She's stressed, I'm stressed for her, it's a whole thing.

She needs British English specifically—her supervisor is a stickler for UK spelling and grammar. "Color" vs "colour" type stuff. Also needs someone who understands the UK grading system (they do things so differently over there).

I've narrowed it down to two services based on online reviews, but I'd love input from actual users:

EssayBox

• Pros: Been around forever, lots of reviews, seem to have UK writers
• Cons: Mixed reviews on Trustpilot, some people say quality varies wildly
• Price: Mid-range, not cheap not expensive

RoyalEssays

• Pros: Modern website (lol), good reviews on SiteJabber, claim to have UK-native editors
• Cons: Newer company so less track record, some reviews feel maybe fake?
• Price: Slightly higher than EssayBox

Has anyone here used either of these recently??

Specifically for:

• Social Science topics (Sociology major)
• British English required
• Need proper citations (Harvard style, not APA—why do they use Harvard over there??)

My cousin is paying out of pocket (no rich parents here), so we can't afford to waste money on a dud. If you've had a good (or bad) experience with either, please share.

Also open to other suggestions if you know a service that's actually good for UK students. Bonus points if they understand what "dissertation" means in the UK context (it's different than US, apparently).

Thanks in advance!