Hi noel, the problem you're having is not to do with the buildings size or age, it's the fact that it is vacant and more susceptible to vandalism or theft and is seen as a much higher risk to take on. Is the bungalow a holiday home? If so this may help but it will most likely still be expensive also an alarm on the building will also help. All I can really advise is to shop around or try a broker but I'm afraid it will most likely be more expensive than standard home insurance.
Best of luck, Bear