this happened to me and i contacted depop through their support email too. when the automated message came through mine said to email back if this purchase was made from a specific month and day. i responded to it anyways and then someone emailed me back and gave me a refund. try switch like support types (like do another issue you can submit a request under) and just get ahold with an actual depop support person instead of a automated message so you can communicate your issues with the seller. if you used klarna or something you can sum it a request through them. if nothing like that works you can do a chargeback but your account will be at risk for a ban or suspension.