Guest 9593

I purchased a one bed ground floor flat in an old Victorian coverted house containing 4 flats last year. There are 2 on the ground floor one with it's own separate entrance and mine and the 2 upstairs flats share the communal front door. I have put it back on the market and the buyers solicitor are asking for a fire safety assessment certificate and an asbestos report. One of the other owners tells me that they had a fire safety assessment done around 20 years ago and had fire doors installed to all the flats and a firewall installed between the two ground floor flats. The problem is that none of the owners can find the paperwork and when I bought my flat last year my solicitor was aware of this but didn't insist on a new one being done prior to completion. My question is therefore do I need to get new certificates before I can sell? And if so any idea on cost? Many thanks