Usually, Paypal operations such as refunding are best done on the actual Paypal website, not the app. Try on the website, and if the problem still persists contact PayPal.
If it was a credit card purchase with PayPal Here you should process the refund through PayPal Here. I just checked on my Samsung Tablet with PPH version 2.8.3 Buld 3294 and I can modify the refund. Make sure you are at the right transaction from the activity list. Tap the refund option. A field is filled in with the full amount. Below that is a number pad to use to modify the amount.
Thank you for your reply. Im not sure then why i am not getting the option to give a partial refund because i am doing what you say and all im getting is THIS...
Well, you didn't mention that this was not a U. S. transcation. It may have something to do with the refund regulations for U.K. and EU. They have complex distance selling regulatations.
I am using the same version and build number as you, and i have just checked and its the same app for both US and UK so im not sure whats going on. Ill give them a ring tomorrow then post the solution on here in case anyone else has the same issue.
