Click the Help button. Chat, email or call is listed under there.
@Judy_F is right that you can find our contact information in the Help Center by clicking the "question mark" at the top right of the page when logged into your account.
However, I will also provide you their direct line here: Billing can be contacted directly at 855-229-5506 and their hours are 7AM-9PM EST Monday through Friday.
I hope this helps!