He has to agree to apply for a refund, and then you can fill in the invoice number, just like when he sold it to you. If you apply for a refund, he agrees, but he doesn't confirm it. Just wait for automatic payment. This is more troublesome, so I can only ask him to return it to you:

Before you returned the goods, you applied for a refund on the web page. If you don't apply at all, you can get a refund if you just agree verbally. If it really doesn't work, go and complain about Taobao customer service.

I hope I can help you.