This is Virtuemart 2.x project on Joomla 2.5, i need to be able to reserve the quantity of the products upon add to cart. For example if i have 10pcs of one product the moment i add 5 of them to the cart, the next customer to see 5pcs available. The session should last 15mins. after which if the customer doesn't complete the purchase the quantity is restored. I also need some sort of pop-up notification for this upon the products are added to the cart. The system already has modifications on the custom fields for the products which have quantitites (ex. red bike, 600cc x2pcs, 750cc x4pcs etc...) the reservation of the quantity should be considered for the custom fields too.