Can a Sirius subscription be set up so that it doesn't automatically renew at the end of it's term? I'm currently paying month-to-month, and am considering bumping that up to the 18 month plan. If I do that, I don't want Sirius to automatically renew my subscription at the end of the 18 month term without me telling them to do so. Is this possible? Or, am I safer just sticking with the month-to-month plan?