Fire damage claim rejection!!!!

I bought a new house last year and been living in it for 1 year and 4 months now. We discovered a leak in the entrance hall where the ceiling turned brown from the leak. My fiance decided to repair the problem before the rain season starts. When he opened up the roof he discovered that our fireplace has got a hole in the chimney just above the ceiling which we were unaware of. We used the fireplace during the winter months and had no idea that there was a problem with the chimney. This caused damaged to our roof and burned the trusses and branding. As I have insurance on my house (compulsory) we are covered for any fire damage. Now Hollard came up with a ridiculous excuse stating that it is a defective design and rejected my claim on that ground. How can they reject my claim if I am not the person who build the house and just bought it from the seller. This is not making any sense to me as my home loan was approved and how was the plans of my house approved by the municipality if Hollard now claims it is a defective design???<br> I am very, very disappointed in Hollard and I feel that they will try any excuse just so they don't have to pay out. I am a very unsatisfied client.