That’s not physically possible im afraid.
If you go into your mobile wallet, open the transaction where you sent the coins to bitbns, there is a “Prove sending” button. This opens a webpage which shows the transaction sending to their wallet.
Add the URL of that page to your support ticket (or screenshot if you cant add links) to show you sent the coins to their address.
However, as the deposit page clearly says, if you forget the paymentID they may not credit your account anyway so its all in the exchanges hands. Only they can help.
Good luck and ALWAYS remember to closely read instructions on exchanges or it can lead to a very costly mistake.