Just half an hour ago I accidentially wired to much money while paying an invoice. I made the transfer on desktop in my browser and had to confirm with a phone app that showed recipient and amount - i just tapped "ok". A split second later I realized my mistake. There even is a cancel transaction function in the user interface but it just told me it's too late because the transaction is already processed... Delaying transactions for about 1 minute with a cancel option would be a possible solution. (in this case I mailed the recipient and hope they are honest)