2004 Toyota Prius Tires

I have a set of 4 of these tires for a 2014 Mustang manufactured 4021 and 4121. I have driven on them for 1 full summer of 2022 and the car was then stored for the winter in my insulated garage in Alberta, Canada. The garage maintains 0-5C through the coldest parts of the winter. I have noticed both of my front tires have cracking all across the tread and the rear tires are fine. Reaching out to Pirelli support they say this is called "Cold Cracking" and that these tires are not to be used below 7C. I have told them the car is stored from fall to spring and doesn't get driven below 7C. They say its my fault having the car stored in a garage below 7C which caused the tires to crack and its not covered under warranty. Somehow only my 2 front tires are cracked and the rears are fine. Pirelli says it's not safe to drive on cold cracked tires and they need to be replaced. So now I have 2 brand new tires with 8mm tread depth that are garbage. DO NOT BUY THESE TIRES!!!!