Selling a freehold property but freeholder does not co-operate with solicitors

Hi,

I am trying to sell a flat in England, the building is split into three individual properties and I am the leaseholder and my neighbour who owns the freehold lives upstairs.

I am currently selling my property and the buyer’s solicitor requires documents from the freeholder my neighbor and freeholder although she has no intention to reply. I have been to see her several times and she either ignores my requests or says she knows that documents are required. I believe the confirmation of lease details and buildings insurance policy.

It has been over a year since I saw a building insurance certificate or policy which my landlord is supposed to purchase. I don’t think the building is currently insured as she does not want to undertake any administration.

There is no concern for her to provide the documents and both sets of solicitor’s are now becoming anxious as the weeks pass. I am worried that I will lose the current offer and that the sale will fall through. Would there be any avenues to force her to reply to the solicitor’s requests as I have asked her on several occasions as she does not care.
Am I still entitled to sell my property as a leaseholder and what are the next steps in order to proceed the sale.

Many Thanks