Are brands failing to properly promote their new chatbots?

I recently wrote an article about Pizza Express's new customer-service chatbot. My overall opinion was that it offers a fairly standard booking system via Facebook Messenger – nothing fancy, but practical enough. One issue I failed to mention is that the brand doesn't appear to be doing much to promote it. Which is odd, as how are people meant to use it if they don't know it exists in the first place? Here's a bit more info on this issue and how brands can combat it.