Here's the reply I got from hosting company:
I'm writing in regards to ticket #7080061, on your shopping cart issues.
I've checked your account and the configuration of your settings on the server appears to be correct at this time. It seems that your website is designed with custom coding, and unfortunately we do not provide support for any third-party scripting issues.
If there are any adjustments you need made to the account for your scripts to function, we can assist with those. Alternatively, you can make any necessary adjustments to your PHP settings for the account by accessing your php.ini file within the Control Panel at PHPplus.bml
If you have any further questions regarding this issue, please feel free to reply to this ticket through your Support Console or via email/telephone. Thank you for contacting us.