Almost the same issue.
The mail I recived with the coupon has a note that says *Your travel code expires one year from today. Don´t especify any date, just say "from today" and the email have a date of Saturday, 14 Oct 2017. I tried to use it today, Sunday, 14 Oct 2018, and says it´s expired.
I called to the number that comes in the email and they said there´s nothing they can do because at their system it says that the expire date is 13 Oct 2018. There were no way for me to knew that, as I said, the email don´t especify an expire date and has arrived at 14 Oct.
I´m very dissaponted. Have canceled my trip.