1) If he owes you an extra 1900 AUD alone, who knows how much extra he owes to all his other customers. I was naively thinking that if the database showed a payment had been made, then the payment had been made. Sounds like that's not the case.
UNfortunately true. If Andre is not stepping up I only see the possibility to set a deadline until where people have to hand in claims. If no claims were handed in we would have to assume tehre is nothing else.
2) Unless Andre steps up with a full list of liabilities, what's to stop anyone from claiming they are owed a similar amount? I'm not at all saying your claims aren't honest, but the next guy's might not be.
I thought about this one, as well. There is no easy way for me to proove this. I see two possibilities: 1) I can forward you the complete mail correspondence with Andre incl. headers
2) I can prove on my account that the money never arrived. I'm not sure whether the Database stored to which account a payment should have been gone. if it's the case, it is easy to prove. If not, I can only show, that all payments went always to the same account, except for those mentioned above.