Hackbard23

You are using the Contact Forms 7 Plugin and are angy about the none HTML 5 Support? 
No Problem. With this Plugin u will have the normal Datepicker & Number Spinner from jQuery in your Internet Explorers and other none HTML5 browsers.
If you have Questions or Feature Request, feel free and contact me.

Contact Form 7 IE DatePicker and Number Spinner Fix

Still works on actual WP 4.7.3. but the need to hack the date format in plugin it self makes it bit awkward.

missing set date format

Works like a charm!

Add the jQuery Datepicker and Spinner functionality to your Contact Form 7

spinfly

When using /sample-post/ or /%postname%/ permalinks and a slug consisting of only numbers, WordPress incorrectly interprets this as pagination and doesn’t handle things correctly. This plug-in will send users to the correct post.

Numeric Slugs

Use post titles and slugs made of only numbers.

Contact Form 7 IE DatePicker and Number Spinner Fix vs Numeric Slugs