I've been using Student premium all year long, and I would get charged 4.99 a month. But for the month of Dec (2018) I was charged 9.99. I went to go check my account and it said that student verification was needed once every year. My beef with this is that I did not get any email whatsoever notifying me of re-verifying my student status. I want to be able to cancel the regular premium account to refund the 9.99 and then have Spotify correctly charge me the 4.99.
That really stinks! I would go onto spotify.com and go to the help section. Once there you should see under account & payment the one about payment help. After that scroll down to refund policy and then you can click the contact us to explain your situation to them and hopefully Spotify will help you out.