Site Insurance

Recently got quoted for Site Insurance from a few companies.I replied to one asking if they could do anything on the price as i had received a better offer.
They(broker) came back to say they had agreed a discount(did not disclose) but if I wanted a larger discount I would have to forward my better offer quote in writing and if it is a like for like quote they would match it.
Surely they can either afford to match it or not?

Basically an insurer will may have scope to reduce a price but wont go too far beyond their book rate to get business unless they have written proof of an alternative. They want to make sure they are not getting played for a fool. Though if it was new business for them im suprised they'd even be prepared to reduce.

Peteb,
Is there nothing unethical/illegal for a company to ask you to give in writing a confidential quote given to you by a competitor?