Remortgage: Paying for new lenders solicitors. Old lenders solicitors want £600.

[badhairday]

So I am remortgaging and I am paying for the solicitors working with on behalf of my new lender. My old (current) lender has assigned solicitors to work on their behalf and I have to pay their fee as well... I feel the the £600 being charged by my my current lenders solicitors is a bit high for basically releasing me from the old mortgage. What is the going rate? I am doubly annoyed because I can't find the clause on my contract which states this expense will be incurred. The lender can't seem to gain access to my contract and he can't show me the relevent clause either!