Insurance may not pay out/how to prove liability

Lisarochelle

In June 2018 I came home from holiday to a collapsed ceiling in the bedroom.  My plumber, Ray, adjusted the ball valve and glued two pieces of pipe that had never been connected to the overflow.  This Feb I heard water coming into the lounge through the walls and dripping from the ceiling - it had happened in the loft again.  Ray could not attend and an emergency plumber came.  He said Ray had not done a proper job and followed through to the other pipes - the hot and cold were not connected where they should have been.  He duly replaced all the pipes for me - cost so far £330.  I didn't want to claim on my insurance as I had been burgled 6 months after the first claim but the costs were mounting.  I rang Ray to see if he had any insurance I could claim on and he ranted and raved, made threats about criticism of his work and slammed the phone down. 

I asked the new plumber for a receipt in case required but he said he would then have to pay VAT as I paid by bank transfer - it was during Covid and who goes to a bank at the moment?!  In the end I had to claim but I happened to mention about the first incident and the surveyor who was happily doing a scope of works then decided some of the damage may be due to the original claim and his company told the insurance not to pay out!  I complained and another surveyor came last week.  I was told not to mention anything but he asked if I'd had any claims in the last five years so he was then biased.  He went round with an instrument that tested water in the walls but said it would be hard to get an accurate reading so many weeks after the event. 5 minutes later he said he wasn't getting readings so didn't think the damage is recent!  I am at a loss as his company say without a report from the plumber they won't get the claim validated and although I've asked for a report it has not been forthcoming.  

I am virtually being called a liar by the 2nd surveyor but what chance do I stand against an insurance company - Zurich who I thought to be reputable - when this is what the two reports say.  I have cracks appeared in the bedroom, 4 ceilings are yellowed and there are cracks in the hall and lounge ceilings plus the lounge walls have blow plaster and bumps down the length of the walls.  No way was it like this before but the 2nd surveyor is saying he thinks it is historic and how do I argue with 'professionals'?  I am stressed and worried and just want it all put right.  The first surveyor even said it may be down to the previous insurance to cover as I now know water was leaking 3 weeks before the new policy started but Hastings take up to  8 weeks to investigate.

What can I do short of suing Ray - and that could cost me more than putting things right myself?
How do I prove to Zurich this is a genuine claim?  I have found 2-3 photos with the lounge wall in the background but likely not clear enough and not sure they will believe the date even though on my phone?