I don't drink... I was up working on a project. I am doing what I can to help this guy out. We are not responsible for customer errors and I will not entertain lies.
This is NOT an acceptable professional position. You or your platform is definitely morally, ethically, and most likely legally responsible for a customer's error that is in part indirectly caused by the platform,
notwithstanding the suggestion to the contrary.
Including errors caused by your platform changing the customer's deposit address and rotating out an old one, failing to automatically identify the deposit, or whatever. Even if for your part, you cannot "recover" the deposit.
If the wallet was generated by service, then there is no excuse for the service to say the deposit address was invalid. Nothing gives the service provider the right to hold the deposit there without crediting the customer,
pretending the receiving address to be invalid, because of limitations of the service provider's software.
If the customer deposited to any address ever offered as a deposit address by your platform,
then you are responsible to make commercially reasonable efforts to return the erroneous deposit
up to and including, reimbursing the customer, or crediting them from the service's business funds,
if YOUR PLATFORM lost an old private key.
Obviously, an exchange would not be responsible for losses caused by the market or timing of order fulfillment.