If you are interested in an integrated shopping cart on your site with additional payment options, you may always upgrade to the WordPress. com Business Plan which allows you to install Plugins like WooCommerce, and provides support to you via live chat (as available) and email.
You also may be interested in considering the self-hosted version of WordPress, called WordPress. org.
For information on the differences between WordPress.com and WordPress.org : https://en.support.wordpress.com/com-vs-org/