Failed Cavity Wall Insulation

Cornerwaysuk

Cavity wall insulation was fitted at my house 16 years ago (detached bungalow) over the last few years we notice that we have damp in the winter mainly that really affects 2 x bedrooms that are up against the same external wall. The rooms have high humidity of 70% plus. I was prompted to have it looked at when getting a quote for an ASHP so I contacted CIGA who were insurers, I couldn't remember the installing company and had no paperwork at that time. CIGA told me the installer had gone bust and was now being dealt with by British Gas and a company called Osbornes. I contacted them and gave them the details, after a long while they have finally come back to me stating that as my house has been extended and the installer or insurance company weren't informed the insurance is invalid and no claim will be accepted.
I found the insurance certificate and insulation paperwork and it does say that work on the house needs to be reported to the installer.
My issue is that I couldn't inform the installer as I didn't know who they were as they had gone bust, and if I had informed them what would they actually do? As it happens the extension work is the warmest rooms in the house with up to date CWI. The area of the house that is really affected is nothing to do with the extension and is some distance from it. British gas or Osbornes have not inspected my property at all.
I have had the property inspected by 2 different company's who have drilled holes and checked the insulation and they have both stated there are spaces where there is no insulation, there is damp inside and this was in summer.
What I want to know is, Is the clause in the insurance really enforceable under the circumstances? (seems to me like a get out clause). Can I take this to the insurance ombudsman? I have asked the insurance company for their appeals procedure.
Has anybody had a similar issue and if so how was it resolved.
The likely cost for removal and replacement of the installation is over £5000.
                                                  Regards   

molerat

CIGA is a guarantee and not insurance, a distinct difference with no independent complaints process, meaning CIGA are judge, jury and executioner over the guarantee terms.