Issues with @session_start() in Appointments+

We are getting a conflict with Jigoshop when the Appointments+ plugin is active.

We get the following error:

Fatal error: jigoshop_cart::calculate_cart_total() [jigoshop-cart.calculate-cart-total]: The script tried to execute a method or access a property of an incomplete object. Please ensure that the class definition "jigoshop_product" of the object you are trying to operate on was loaded _before_ unserialize() gets called or provide a __autoload() function to load the class definition in /home/angelade/public_html/wp-content/plugins/jigoshop/classes/jigoshop_cart.class.php on line 499

According to Jigoshop support - the issue with the @session_start() per the following forum:
http://forum.jigoshop.com/discussions/problems/2487-fatal-error-after-upgrade#comment_19691751

I tried making the suggested changes to your plugin but it did not resolve the issue.

Any suggestions?

If you need to see the live example - please send me a method to send you the URL privately.

Thank you