Try calling 1 (888) 444-4410 instead to cancel your order. I've canceled mine and my friends because we decided to get our phones at the Apple Store. Explain to them that the order is still on backorder and that it won't ship any time soon. If your upgrade isn't back within 10 minutes, call 611 and tell them to reinstate your upgrade.
Thanks for letting me know. Well I called that number and they told me the same thing. Nothing they can do because i accepted the terms and conditions, even though its in back order.