Is your mate a regular at that particular bookies and does he back trebles as a rule. If yes to both, he could perhaps appeal to their better nature - yes, even bookies have those! Some years back, i used to do two football bets on a Saturday; a patent with 3 selected teams to win 2-1 and another with 3 selected games to end 2-2. On the only occasion i managed to get all 3 correct in one bet, i noticed that i had omitted to write 2-2 beside one of the games. However, because i had been using the bookies for a number of years and those behind the glass knew what bets i put on, i was paid in full. And that was a difference of about £400 back in the 90s. If your mate is not a regular, then, as has already been suggested, he should thank his lucky stars to have received anything other than his stake money.