A few ways a customer can contact a company's customer service representative is via a customer support line, online contact form, email or live web chat. Contact details for all of these methods are usually available on the company's website.
For example, AT&T has several customer service contact options. The company's website has a live agent chat feature using which customers can pose questions about billing, payments or technical support. The website also provides a customer service phone number and hours of service availability.
In addition to both these methods, AWeber and Staples also have online contact forms. The companies respond via email.