What should I do if I ask for a refund again if I sell my cell phone secondhand through a personal transaction?

I sold my cell phone second-hand through a personal transaction.

They want to get a refund again because the buyer changed his mind.

What should I do if I make this request?

Do I need a refund?

Or can I ignore it because it's a simple change of mind?

1115 2017-04-26 Gentleman

popular Why does it say that your license has expired on your phone?

popular What is the deadline for purchasing lotto?

popular What is the nationality of Minnie?

popular How do I recycle and recycle foil like cooking foil?

popular How can I resolve TLS security configuration errors?

Same Tag Can I get the number from my old cell phone number?

Same Tag When I change my phone, which condition is better, new registration or a number transfer?

Same Tag How can I install Kakao Talk on my iPad?

Same Tag What kind of memo application can I use on my smartphone?

Same Tag Is there an Android keyboard application that's convenient?

Same Time Can I go on a diet with an indoor bike?

Same Time What should I do if I ask for a refund again if I sell my cell phone secondhand through a personal transaction?

Same Time If I want to enter a specific folder in Windows 10, do I need to know the password to make it possible?