They might change thier mind, minimum of £750 I would say, just go around a few places and gets qoutes, tell them it's for insurance they will soon do a quote.
I had a tiny dent in a rear panel by someone else, plus bumper on a mk3 astra, that came to £480, the dent is so small I can't find it immediately looking for it, and the bumper is only £46!!
tabetha