@killie 

You should double check the email address or mobile number of the person you are sending the funds to before sending to make sure its the correct person.

If you sent it using friends/family then you can reach out and ask the 'wrong' person and see if they will refund the funds, if they don't then as it was a 'gift' payment there is not a lot you can do about it. 

If you sent it using goods/services and they refuse to refund then you could open a dispute for non receipt of item (as they have nothing to send you) and escalate to a claim.