Vivexin has a dedicated US-based customer service team, with email representatives for faster service. They can also be reached via postal mail at the following address (which is also the return address for cancellations and product returns under their money back guarantee).
818 SW 3rd Ave #220
Portland, OR 97204
For all other issues that cannot be solved by email or postal mail, and that are not addressed in the Vivexin customer support forum, their phone number of (800) 371-0168.