Sirius' cancel process is absolutely painful. People reading robotically from scripts that don't sound convincing even to them. "Did you know that we now have award winning X? Maybe you would like to listen to that on your [insert car here]".
Just repeating "No, I just want to cancel" and nothing else doesn't help, either.
On the flip side, they have offered me ridiculous deals. As of right now I have the Music Showcase subscription for 2 vehicles (meant to be $13.99/mo each) for "$7.99 for 6 months, for both vehicles" - as in $7.99 for the entire 6 months, not per month, and for both vehicles, not each.