Stamps.com Charged my card - I had no idea and they would not reimburse me El Segundo, California

Because I used it to print a paid shipping label. Once. Didn't realize I was signing up for a monthly service.

Hi Craig,
 
Stamps.com apologizes for any misunderstanding during your signup process.  We offer a four week no-risk trial during which you may try out our online postage service to determine whether or not the service fits your mailing and shipping needs.  However if you do not cancel the Stamps.com service and go past your four week trial period, you will be charged $15.99 for using the service during that first "trial" month.  After you pass the four week trial period and become a regular customer, you will be charged $15.99 each month moving forward.
 
You mentioned you did not see any language indicating the monthly subscription, however, during our registration process and before customer accounts are created, (on the page called Postage Account Credit Card Authentication) all prospective customers see the following text:
 
Why do you need my credit card information? 
Your credit card is required by the USPS to set up your USPS postage account.  Your credit card will not be charged unless you buy additional postage or Stamps.com products, or if you continue past the NO-RISK 4-week trial period. 
 
We provide and disclose terms that we do expect all potential customers to read, review, and agree to before they create their accounts.  Accounts cannot be created without customers indicating that they have read the terms by clicking on the I Agree box. 
 
Again, we apologize for any misunderstanding and would be happy to further review your account. Could you e-mail us your full name and phone number to social@stamps.com?
 
Thanks!
Divya
Stamps.com

Why did you give them your bank info for a service you didn't expect to pay for?