You need that break down, of the first agreed price and then the additional costs.
I'm surprised that you have paid anything, the norm, i thought, was that on closing day after the receipt and clearing of the bank mortgage cheque, there is usually a refund due of some part of the deposit from the vendor, which goes to your solicitor and then he deducts his fee from that and pays you the balance. In my own case I had to put down a deposit of 10% but the mortgage was 92% so there was an overpayment by me of 2% which was returned to my solicitor...he then took his fee and sent me a cheque for what was left...
And as I always say...if the solicitor's explanations dont stand up, there's always the Law Society