Add to cart not working

[Jörgen]

This is a long shot, You are working in http, should use https for your website. Do you by chance have https activated for sensistive areas like checkout. Setting in VM back end for this ...

Jörgen

[jenkinhill]

I just dug a bit more into your page code.
This CSS file 
http://timb103.sg-host.com/plugins/system/vmuikitx_onepage/vmuikitx_onepage.css
is obviously installed, so you must have been using VMuikit X OPC which is a plugin from joomlapro.com. This appears in plugins as VMuikiX
See https://extensions.joomlapro.com/support/documentation/vmuikit-x?showall=1 for what it does.

[GJC Web Design]

if your geting messages like ->  http://timb103.sg-host.com/plugins/system/vmuikitx_override/html_override/com_virtuemart/assets/js/jquery.elevatezoom.js

then obviously the system plugin vmuikitx_override is still active

and as for  ->  http://timb103.sg-host.com/templates/beez3/html/com_virtuemart/themes/default/assets/css/custom/vmuikit.css

in standard Joomla there is certainly no such folder as  templates/beez3/html/com_virtuemart/themes

this vmuikit crap seems to have altered your actual folders and files

plus you should be using https on any site no days