Most likely, it'll be a bug in B.info wallet... honestly, it is one of the most poorly coded systems (both web and mobile)... I don't know why it is so popular??!? 
It is probably caused because the wallet doesn't know how to properly reconcile the fact that it sent 0.00792085 BTC TO 1FYyHeSHy47NTiEBBYs3HAwsss8b3oYK3N and then received 0.00792085 FROM 1FYyHeSHy47NTiEBBYs3HAwsss8b3oYK3N... and the values cancel each other out.
You have the actual blockchain as proof you returned the coins, he will need to sort it out with B.info (probably delete the app data for his wallet app... and restore the wallet from seed or repair it or whatever system b.info use )
It is probably caused because the wallet doesn't know how to properly reconcile the fact that it sent 0.00792085 BTC TO 1FYyHeSHy47NTiEBBYs3HAwsss8b3oYK3N and then received 0.00792085 FROM 1FYyHeSHy47NTiEBBYs3HAwsss8b3oYK3N... and the values cancel each other out.
You have the actual blockchain as proof you returned the coins, he will need to sort it out with B.info (probably delete the app data for his wallet app... and restore the wallet from seed or repair it or whatever system b.info use )