Somebody I don't know sent me money and I don't know why

[Tychob]

They actually sent two transactions. I refunded the first from my paypal balance but I can't refund the second without it coming from my bank account. I am not paying to give their money back. I want

- The transaction to be cancelled, and

- Them blocked so they can't do this again

Any idea how to do this?

[Tychob]

I gather it isn't possible to refuse money?

They've now emailed me, insisting it was a mistake and demanding their money back. I can't give it back without paying the PayPal fees myself.

I don't sell anything. Nobody ever sends me money. Can I set up my account so all incoming money is automatically refused?