I'm signed up for the student subsription, and I get $4.99/month. I just bought a $10 giftcard and it only counted for one month.
Thanks for the help.
Gift cards cannot be used with offers or discounts.
$10 gift cards will only count as one month (regular month costs $10)
They will tell you the same thing, but if you wish to contact support, you can do so here: https://www.spotify.com/about-us/contact/contact-spotify-support/
If you get an automated reply email, you need to reply back to it.