The experience of selling on Amazon is by quite a long way the most frustrating and badly designed experience I've ever had online. It's hard to know where to start. Nothing is intuitive, the UX flow seems to take you round in circles and if you can finally find how to raise a ticket, the support is terrible. Sometimes after two or three responses you might get a helpful reply, but you'll be pulling your hair out in frustration in the meantime.
Amazon claim to be obsessively customer-focussed, but it's a shame they arrogantly abuse their near-monopoly position and don't appreciate sellers as customers.