Why GitHub educational promo is not for students? Is DigitalOcean a lier?

2 days ago, my college IT department told us, there is a package on GitHub for students. We registered to that service, and today I wanted to add my 100$ promo code to my account. But DigitalOcean said “you can not use this promo code, because you are an existing user.” I said OK, I’m going to create a new account, and they said “Sorry, you neither use code on a new account”. What kind of a joke is that? Is DigitalOcean really that much miserable? Tell me a way to use that promo code, or apply it on my account!