Problems with Contact Form 7

Hi,

This is more of less a situation that has arisen as I upgraded my PHP to 7.0 from 5.6. I did it on a WHM Multi PHP manager.

* WordPress most recent version
* Plugins all updated beforehand

1 – Theme “X” – 2 sites: contact forms disappeared completely.
2 – Theme Joeby – 1 site: Broke all pages behind homepage. Once I deactivated Contact Form 7 form – all pages returned.
3 – Theme “Responsive” – 1 site: Threw errors: ERROR: si-contact-form.php plugin says GD image support not detected in PHP!
Contact your web host and ask them why GD image support is not enabled for PHP.
ERROR: si-contact-form.php plugin says imagepng function not detected in PHP!
Contact your web host and ask them why imagepng function is not enabled for PHP.

These are the first few of probably 10-12 sites that contain Content Form 7.

The PHP 7 upgrade seemed to trigger the behavior.

But having to switch to a different plugin for contact form is ridiculously time consuming. Any developer suggestions for situations #1 and #2 above??
Thanks!