Solicitor said no win no fee but looking for money

Quick one, I had a case of medical negligence taken up by a solicitor on a no win no fee basis however I had to pay for a number of medical reports myself to the tune of the guts of 10k. Anyway they said the reports didn't provide sufficient evidence so I'd have to try get another. I told them sod that as I'm not spendimg more money with nothing guaranteed.

So now they have said they need 500 euro in fees owed! 250 odd of which is "admin fees" which strangely brings the total to exactly 500 euro. Do I have to pay this as I was told no win no fee?