You don't have a choice. If you live in the US, and maybe other places, they have your credit information and will sell your info to other companies without your consent. It's an opt-out program where you have to pay to opt-out. Makes no sense to me. The way it should work is that they contact me every time someone requests a credit report on me (could be through phone, e-mail / IM, etc.). Then I give them permission if I want the report to be released. That would stop most credit fraud. Instead, they just hand over my personal financial information to anyone willing to pay for it without even asking me. It's a very broken system.
Sounds suspiciously like identity theft, the way you put it.