Tuff Shed review: Roofing

This was the first of two Tuff Sheds I purchased. After some windy conditions, I was checking the roof and found shingles off. Upon looking inside, I could see daylight coming through. I was told the space was for expansion? Was also told, underlayment was only put partway down...Really! Reason? I was told this was standard installation procedure. Though my warrantee had expired the year before I felt this type of installation is unacceptable. For $1416.52 they would come out and repair it.