I have a e-voucher from Delta airlines. One of my friend has booked a trip from detla which includes me too. How can I now redeem my e-voucher on the already booked trip?
You can always try calling Delta and see what they say, but unfortunately Airlines are usually pretty picky on these types of things. I am certain that there is no way to do it online with an already existing reservation. Who knows? Maybe you will get a really nice agent on the phone who can pull some strings!