Hello.
Let's imagine that we have configured our shipping that when order has value of $100 or more its shipped free.
Now we want to buy something worth $20 and do not pay for shipping. How to do it? Simple - add the product you want to buy, and then something else so the order exceeds the $100. Then start placing the order. On the shipping page you should have information that the only shipping method available is the free shipping. When you got to the confirmation page (step 3) on a new page/tab open the shopping cart page and remove the product(s) that you do not want to buy leaving just the one you want - make sure you confirmed the changes in the shopping cart. Then go back to the page/tab when you are stopped at the third (confirmation) step and click the button to place the order.
Your order will have only one product for $20 and free shipping.
If your shop does not have many orders then you probably notice that there is something wrong with the order, but when you have them more it could slip through.
We are currently using 1.3.7 version of ZC (and getting ready for upgrade) but as far as I got to look into the latest (1.3.8a) ZC code there should be the same bug.
The solution would be to check in the checkout_process module if the shipping module is still available for the order. You could also imagine that there could be some payment modules that are available only in certain price ranges so availability of those modules should be checked also, I think. If module is not available then client should be redirected to the proper page (checkout_shipping and checkout_payment accordingly) - maybe with some message.
My best regards
Maurice




