To communicate directly with purchasers or vendors on WhatsGood, send them a message within their order summary.
Click on the orders tab in the left hand menu, search for the customer would like to message.
Select the order you'd like to make a comment within
Scroll to the bottom on the customer's order summary page (example below)
Draft and post a comment within the thread. The customer will be notified of your message and has the ability to respond within the same thread.