One of my people @3djanole let me know that Amazon will give you a free month of Prime if they miss a shipment date. Here’s a link to the rules. You can read the rules in the link, but what you want to know is this:
Note: If you received free shipping through Amazon Prime, you may be eligible for a free one-month extension when the promised delivery date isn’t met. Prime Extensions are limited to one per free trial and 12 for an annual membership. Free Amazon Student Memberships do not qualify for this extension.
Please don’t abuse. I’m surprised they are this generous to be honest.