Authorize.net users How do I recalculate shipping?

The way my shopping cart is set up the shipping is determined after the sale (because not all items are shipped from the same are or same service) I have a note at the checkout that says "Please Call for your shipping total so that we may give you the best possible price depending on items ordered and your location."

I would like to be able to add the shipping cost after the card is authorized in Authorize.net but it will not let you increase the amount charged to the CC only decrease.

The only way I can think of doing this is by storing the full CC number and re adding the sale myself with the correct shipping amount.

Any better ideas??? Please???

You can't increase the total charge after the authorization because the card was authorized for that exact amount.

The way we handle it is to allow calculation from our distributer who happens to be in the mid-west. We have another distributer on the west coast and one on the east coast as well, but by having it calculate from the mid-west we're getting what I would call the median shipping rate. Not to mention that that distributer gets a great deal from ups due to their shipping volume.

So by using the distributer with the median shipping rate you're giving most your customers a great deal on shipping. Those that pay less than the shipping cost we tend to let slide, those that pay too much we tend to give a refund for the difference. You don't want to overcharge because they won't come back.

Most of the customers will actually email us saying that the shipping is a bit high and they want me to recalculate it. I inform them that if they go ahead and purchase I'll refund them right away. They appreciate the customer service and have even referred customers to our store.