Trying to order 12 items, but getting a higher rate than the real rate

Customer:

A customer is trying to order 12 items, is getting a higher rate than the real rate returned by USPS here.
Parcel packing is set to Recommended: Pack into boxes with weights and dimensions

Support:

This may be happening because the 12 items cannot fit in the box created by you.

Since you have selected “Pack into boxes with weights and dimensions”, it is mandatory to create boxes by providing dimensions and weight. We hope you have provided the dimensions of the box such that they fit into one box. You can create boxes using the “Add Box” button in the plugin settings page.

We hope you have provided the dimensions of the box correctly such that they fit into one box. You can create boxes using the “Add Box” button in the plugin settings page.