@holydarkness this is not about a proof that a warning was sent from Betby to XYes, this is about proof that there was arbitrage betting. For that you would need to have 2 bet slips, both with comparable stakes on the opposite outcomes of the same event. This is not do-able on the same bookmaker (because they have a bookie margin that makes it impossible to arb within the same book) so the 2nd betting slip would have to be from another book (for example Pinnacle) and it would be impossible for you nor XYes to have obtained this.
You have a valid point here, and BTW football having 3 options actually means possibility of 3 bets lips to balance up the equation of stake 1, stake2, stake 3... but then again arbitrage betting evidence is never put out in the open, its an internal thing that is for their eyes only especially that the other bets are placed on other Sportsbooks..which means evidence can not be technically made available without crossing some red tape and possibly getting the misuse of data.