Chevy Silverado 2500 Floor Mats

Ordered 2nd row floor liner for a 2021 Chevrolet 2500 without the under the rear seat storage. I thought it would cover the entire carpeted area, to include under the rear seat. It does not. The mat looks like it should be for vehicles with the under seat storage. The box it came in says that it is for the vehicles without the storage under the seat. Also, do to it not going all the way to the back of the cab, the mat keeps sliding back, even with the keepers installed that came with it.