I can't find the abandoned-cart feature in my panel — does it exist?

It does — Marketing → the 'Abandoned carts' card, under 'Bring them back'. It opens straight onto its own section: turn it on, choose how long to wait and what to say. When somebody fills a cart, leaves their name and number and does not order, a message is prepared. If that person has messaged your WhatsApp before, the reminder is sent by itself in the daytime window, under your weekly cap. If they never have, it waits on the Marketing review tab for you to approve or discard. In both cases nothing is sent if they place an order in the meantime. If you don't see the card at all, it is part of the promotions plan features.