THE PROTECTOR DOESN'T FIT MY MATTRESS PERFECTLY. WHAT SHOULD I DO?

The great thing about that skirting material: it might appear larger right out of the package, but it'll shrink to fit perfectly on the bed once it's on. The sides are fully intended to be tucked into the foundation or frame if necessary. If you are finding it to still be on the bigger side, give it a quick wash and it should be fine!