Did they agree that with you in advance? If so, yes. If not, it may be an hourly rate, or a pre-agreed rate. (which you do not appear to have)
I think you need to contact them, and see what they actually say (and get it in writing, with a breakdown, including VAT).It will be dfficult for anyone to judge what is reasonable without the particulars and what was agreed.ie, you need to phone them and see what they say, then get it in writing.
If ithe amount seems unreasonable, you might post back here for further advise?
Nicola