If you paid via Paypal and its within 180 days of that payment then they do not need any information as all they have to do is click on the transaction in their Paypal account and scroll down and click on the refund option.
If you did not pay via Paypal or its over 180 days then all the seller needs to send you funds is your Paypal email address OR your mobile phone number if using the app.
Advice is voluntary. Kudos / Solution appreciated.
