there seem to be two threads...I've posted my other issues with this mod breaking my cart elsewhere...

solved the above problem by running the update sql file in the mods folder

BUT...BIG BIG BUT....this issue with the quantities not updating and the customer being able to check out with things not in stock is a deal breaker.

I've replaced the shopping_cart / header_php.php file with the one from Kuroi's MULTIADD mod and that helps but the style sheet suddenly dropped out of the admin.