A telemarketer took money from my checking account even though I did not agree to buy anything. Can I get the money back?

If the check was processed as an electronic transfer such as an ACH payment, you have additional protections under federal law.

In addition, the FTC Telemarketing Sales Rule requires any seller to get verifiable authorization (unless you pay by credit card or debit card), which means the telemarketer must get either a written authorization from you or a tape-recorded oral authorization. If the telemarketer chooses written authorization, it must send you a written confirmation of the transaction by first class mail and let you know of the procedures to receive a refund.

You may also have state law protections.