Ceiling collapsed after work on my roof, entering factor hell

Sanchless

Hello MSE folks, your forum has always had useful information found through google, I'm hoping you can help me now in my desperate time of need.

I purchased a top floor tenement flat in Scotland almost two years ago. In December 2014 we found that the excessive rain was leaking into our flat through the roof and attic in two locations, the living room and my spare bedroom. We made the factors aware immediately and after much hand wringing and phone calls managed to get them to do a temporary repair a few months later. They have finally got round to doing full repairs in the past two weeks and workmen have been on the roof.

I noticed a crack in the ceiling last week. This weekend, about a quarter of my spare bedroom ceiling collapsed (adjacent to where the leak was). The room is now coated in rubble and dust, a few things in the room are probably beyond salvaging (the carpet for example).

The contractor working on the roof at the moment confirmed that it could not be their fault as they have not been working in that area of the roof. I believe this, as they do not have scaffolding set up. The surveyor who has been hired to supervise this work took a look in the attic and commented that what it looks like to him is that the area that has collapsed was previously a poorly done repair job which was painted over (before I purchased the property). He said it is likely that when the temporary repairs were being done at the start of 2015, the contractors could have stood on the slats and weakened the ceiling, causing it to eventually collapse over time. He found a polythene sheet they had left in the area to stop previous leaks but that the area is currently dry. He said this to me verbally and said he would be in touch again after speaking to his boss (3 days ago, nothing yet).

I have spoken to my own insurance company, and I am covered for accidental damage; however, as I understand it I need to provide them with an independent report confirming the cause of the collapse. I imagine this will include evidence from when the temporary repairs were done by the previous contractor, but it seems hard to conclude from some dark photos taken at the time. What if they didn't take photos or refuse to provide them to me?

My factor has unsurprisingly not been particularly helpful. They have not set any clear path forward and getting messages between the parties (contractor, surveyor, factor) seems painfully slow. Are they legally required to fix things within an amount of time? I can already tell they're not going to be too fussed about helping me with this.

Just looking for general advice really and opinions on what I can do to get this sorted ASAP. Thank you.