In the car of Sirius it's pretty amazing the lengths they'll go. They send out a Customer Agreement with a welcome packet when they activate a trial subscription for a particular unit (usually when you buy a car, new or used, but I've received it on my car that I bought 4 years previously). That agreement, it claims, has the power of contract, and will be binding on the customer as soon as the service is activated or the customer receives they're policy. Of particular offense to me, it subjects the customer to binding arbitration (for a trial subscription the customer never requested or affirmatively agreed to). They've literally gone to the Supreme Court (and lost) arguing that a trial user could not sue for their nuisance mail because of the arbitration clause. The agreement states that it remains in effect unless the customer cancels their (trial) subscription within 7 days of activation, and only by phone.

In my most recent case I received such a packet 6 days after the date they said they activated the service. I called the same day and told the agent I wanted to cancel my trial subscription, citing specifically that I did not want the service and refused the terms of the agreement. The retention script (which is the same no matter which agent you talk with) is, "well you can keep the trial going and it will just expire", and repeat it several times. You have to be persistent and use the language "cancel my subscription", or you will get nowhere.