First-purchase delivery discount lost after seller failed to send item

I recently made my first Vinted purchase, a £4 hat (postage was £2.29, but Vinted applied a £2.29 promotional discount, so I paid £4.90 including Buyer Protection)

The seller didn’t dispatch the item within the deadline, so Vinted automatically cancelled the order and refunded me. The seller then relisted the hat, but when I tried to buy it again, the free-delivery discount had disappeared and the new total was £7.19

I contacted support and initially received several replies that didn’t address the question. Eventually they said that first-purchase delivery offers are treated as used once a transaction is initiated even if its cancelled because the seller fails to dispatch. They said they couldn’t restore the promotion/regenerate it/add it to another purchase/give me an equivalent £2.29 Vinted Balance credit. And I was trying to resolve it the relisted hat was sold to somebody else anyway

Has anyone else had this happen? Did your free-delivery offer ever return automatically or did you find any way to get Vinted to restore it or provide equivalent credit? It seems very unfair that the buyer loses a one-use promotion because the seller didn’t fulfil the order