Woo-C Order Delivery Date Ext. Issue

I’m using the WooCommerce Order Delivery Date extension, and I’m following the instructions as to how to specify dates when shipping is not available (in this example, 12/26).

If I add that date to the shipping calendar (or the delivery calendar) — I can still select 12/26/16 as a delivery date on the checkout page.

The only way the customer knows the delivery date of 12/26 is unavailable is by filling in their credit card info and then submitting the order. The order then fails with the obscure, yet definitive message that says “Delivery Date is not a valid date.” The customer is then left to surmise that they must select a different delivery date, and then re-enter their CC info and submit again (and from their point of view, hope the next date is valid).

How do you set this up so that the dropdown calendar itself does not allow the blocked dates from being selected in the first place? The problem with the way it’s set up, is that if you’ve blocked a week where you cannot ship out, then your customer may very well try and fail five times before simply giving up on the order.

Common sense dictates this be addressed in the calendar dropdown, and not in an error message.

Am I doing this wrong?