Usual agent company will not and is not able to "polish" your personal statement, they just refer you to specific Uni, fill-in form at UCAS sort of thing. For consultant who help you to "polish" PS, they are lot more expensive.
They have many packages ranging from full consulting/counseling service for 4 years prior to university entry (charge 6 digit number) to simply helping on PS (UK)/Essay on Common application (US) (charge 5 digit number). You can call them for specific service on your case. They usually called university consultant / counselor (not agent).