Where is the most unlikely place to find an empty ice cream package/box???

My mother sold her house for 7 years ago. Now the buyer of the house contacted my mother and claims that it has a hidden fault and wants a lot of money (60000-80000 SEK/8000 EUR) to repair a leak on the roof. He also claimed that my parents had put an ice cream box inside the ceiling to gather water. This ice cream box should have appeared when they opened up the ceiling. So my old mother is now upset as she has pointed out to him where it is possible to get a leak and how to avoid it. Also she had paid for an inspection of the house and other houses had this problem which the new owner was informed about. I have never heard of someone who found an ice cream box inside/above their ceiling and it was definitely not put there by us. My mother won the case and the new owner has to pay for it himself...but come one..an ice cream box!?