I would like to insert the necessary booking number in my wire transfer email.

Please help me.

I already explained why the booking number is not included: because at the time we use the gateway and send the email (when hitting the submit button), the booking number is not yet created. It is created only after the booking is inserted. If we execute the code that sends the bank details by email after the booking is inserted, then we can`t add a check to see what gateway has been used, so the email will be sent no matter what gateway was used. So, I guess the best solution is to add a note to that email and tell your guests to include the booking number when they made the payment and that the booking number can be found in the other email they`ll receive.