Your theme overrides ALL WC Vendors Templates? That’s pretty weird, you should only be overriding the ones you actually are modifying.
PHP 5.4? Ouch. Get at least PHP 5.6+, preferably 7.0.0+
No child theme? Asking for trouble! Child theme your site before it gets to be too hard/complex. 🙂
Lastly, check your site url in wp-admin > settings > general, as well as your permalinks (wcvendors.com > kb > setting permalinks)