If you have decided on having a model dissertation prepared by an academic writing company, I would strongly suggest that you ensure the business is UK based, and employs people whose first language is English.
However, have you considered the option of creating your dissertation from scratch, and then having it edited? This can be a really useful service for students and can certainly help boost a classification.
Feel free to contact me if you require any further assistance or advice.
Regards
Caroline
Critical Proof Ltd