Complex sentence: Authorize.Net sells its services to merchants both directly and indirectly through re-sellers, and a merchant wishing to use Authorize.Net's payment gateway services can contact either the Authorize.Net or a reseller.
Split into simpler sentences: Authorize.Net sells its services to merchants both directly and indirectly through re-sellers. A merchant wishing to use their payment gateway services can contact either the Authorize.Net or a reseller.