Don't consider the environment - Print the receipt!

Yesterday, I gave a total stranger 500 Riyals. It was an accident of course. I was trying to send 500 Riyals from my credit card to my mobile phone, using a Qtel ATM. Perhaps it was too early in the morning, but I made a single digit error in entering my mobile number. Worse, I 'considered the environment' as requested on screen and opted not to print a record of the transaction. Big mistake. Half an hour later, when my credit balance was still in single figures, the truth began to dawn on me.
Fortunately, I was fairly sure I knew what wrong number I'd credited. It hadn't been a finger slip; I'd deliberately entered and visually checked a number that I often think is mine, which ends in a 2 instead of a 7. I misremembered it that way years ago, and can't get it out of my head.
So, I texted the right wrong number and asked him/her to check if s/he had a richer phone than expected. No answer. I called the number. Still no answer. I resigned myself to my loss and sent myself another 500, this time to the correct number. And I took a receipt!
This morning, I received a surprise call, from my 'wrong' number. The caller confirmed he'd received an unexpected credit at the correct time and reassured me that he would return it. But, to protect himself, probably in case I was some kind of scam merchant, he wants to see the unprinted transaction receipt first. Tricky. He's agreed to settle for a glimpse of my online credit card statement instead. That will take a couple of days to register, after which, with luck, he'll transfer back the balance, giving me an unprecedented 1,000 Riyals total credit. That should keep me talking for a while.

Postscript: He was good as his word and duly refunded my 500 riyals on a sighting of a screen grab of my credit card statement (with sensitive numbers obscured, of course).