When the paper is not yours
Half the people who order this are acting for another person. A manager settles a new starter's file, a son sorts out his father's affairs, a wife handles a husband's record while he is away at sea. None of that is a problem in itself, but it opens a gap between you and the paper, and nearly every error in these jobs lives in that gap.
The language Dominican Republic requires
Dominican Republic reads these files in Spanish, so the whole record goes into Spanish before it is any use there. If you are acting for someone else, show them the finished pages anyway. They will catch a wrong second forename or an old address faster than you can, and an official Spanish translation in Plymouth is far easier to get right once than to order twice.
Who signs, and what the signature covers
The translator signs a certificate of accuracy under their own name, and that is the whole of the credential this route needs. It says the Spanish matches the page they were given. It does not say the page is yours, and nobody is asking you to prove a family tie or an employment link, so acting for a parent or a member of staff adds no step to the work.
Per-page cost and turnaround
Count the pages of the record and multiply by £25, and you have the cost before you talk to anybody about money. Turnaround is 2–3 business days once a clear image is in hand, and 24 hours on the faster option. Both figures help when the paper is not yours, because the person waiting on it usually wants a date rather than a promise.