Deposit is only lost if you don’t follow the trade protocol - which you did.
If the error isn’t on your side, you will get your deposit back.
You should double check the IBAN again, to make sure you didn’t spell it wrong. Once you’re certain that you can’t complete the trade with the information given to you, opening a ticket is the right way.
After all there’s no point in waiting 6 days in that case.