Before I commit to a Support Ticket. Can you please confirm the following.
By creating a Support Ticket I will receive:
1) On success of payment the quantity Purchased will deduct from the stock amount in the products database.
2) On the Cart Page, the checkout button will only appear if there is enough stock for the quantity of products in the cart.
3) The add to cart button on product detail pages will only appear if the product is in stock.