I believe you should be taking this up with the owner NOT the OC. I’m not sure whether a tenant can submit an insurance claim on the building insurance (I suspect only the owner can do this).
The only thing the OC is reasponsible for is to submit an insurance claim against the (lots fixtures and fitting) Building Insurance. What is the insurance excess if is it greater than your claim if so no claim is possible.
I also suspect insurance claims have to be lodged within a certain time scale and I would suspect 4 months is well beyond that.
Your claim must be against the owner (he should be claiming on the building insurance) as it’s NOT common property but lot property.