The administrative fee that this agency charges is crazy. 14 days +VAT of the rental. For a £1600/mnth property, they want £900 inc VAT. That is mental for printing a bit of paper and running a few checks. Other agents in the area charge half of that. Avoid is my advice.
What agent could do to change your mind?
Charge for the services being undertaken rather than ripping off tenants. Why not charge a flat fee per tenant instead, not a percentage of the rental value.