Household insurence declined as insurance assume leaking gas inside is part of negligence

I put a claim through for household insurance they got their assessor and declined my claim as they said that my fridge were leaking gas inside of the fridge and they see it as part of negligence or wear and tear. The fridge is more than 5 years and warranty is finished. There was no problem before as electricians inform me to re-gas which i have done now suddenly I put a claim through they decide that it was negligence as i am not an electrician or technician to know if a fridge is leaking gas inside. These insurances are just running away and make excuses to pay but they can deduct your instalment and give you increase it as they pleases without complain.