I was recently on the Xbox Live support line to cancel my auto renewal (Which is annoying btw, but thats another story) and I asked the guy to turn it off. I was then offered a 40% off 12 month subscription for when I next needed to renew. I had no intention of cancelling Live I just don't like money dissapearing out my bank without my knowledge.
Anyway the point is that you can ring up and threaten to turn off auto renewal and you may get offered 40% off 12 months like I was (£22.99 if your UK like me)
Just thought I would pass that on, this may already be common knowledge in which case I apologise just ignore this.