You can, of course, report your ongoing transactions as usual if there is a problem with an item after receiving it.
You report the transaction in the usual way by going to Purchases > My Purchases > Find the relevant transaction > Report an issue with the transaction.
Until November 10, 2024, you can still contact Trendsales Support if you need help with a Trendsales transaction.
If you need help with a transaction that took place on Vinted, please contact Vinted or report the transaction via the Vinted platform. You can contact Vinted here, where you can either contact them directly or find answers to your questions in their help center.