Hello,
Welcome to the forum.
Unfortunately, Vinted automatically imposes its own carrier, and there is nothing more you can do.
Try contacting Vinted about this? There seems to be an issue with the carriers, we are already discussing it on the forum here 
Impossible de voir les points relais proches de chez moi or here Service point relais non disponible, nul part en france, alors que disponible avant
I am closing this one as a result 