apple music

So a little backstory first I signed up with apple music for the student subscription. I signed up for student sub at the end of March. I thought I was paying 4.99 a month since April until I noticed that my card is still being charged regular subscription. But when I look at my apple music subscription it says it has been changed to a student and that I should be paying 4.99. So my question is how come I am getting charged 10.99 a month, instead of 4.99 even though my phone clearly says I signed up for student?