My Live membership expires tomorrow and I've got a 12+1 month card coming in the mail. It won't arrive until after my membership expires, so how do I keep from automatically getting billed for 12 more months?

I go to the 'Manage Profile' section on Live and the only options I see under 'Modify Membership' are Month-To-Month, 3-Month, and Redeem Code with an automatic $50 12-month renewal coming up tomorrow.

I thought I could just delete my credit card number under Billing & Contact Info, but I only see my address.

I've got a 1 month Live Gold trial card from when I bought GTA IV. Can I just use the code from that to extend my membership? I don't see any mentions of 'New Accounts Only' in the fine print so maybe it'll work?