My client wants to offer free shipping on orders over $20 (selling cards). Currently I have it set up so the default shipping is $2. If the order is $20 or more, the Free Shipping option appears in a second radio button. But, because the default is Free Shipping, the purchaser must choose Free Shipping for themselves. This will lead to many errors and needless refunds! The site is at http://sitka.first-encounter-design.com and the issue can be seen on the Cart page.
Is there a way to have the Default shipping method change to Free Shipping if the total is over $20 or more? It would seem there is a way to do this through php, but I don't know how to do that. Can someone here help?