Higher amount was charged after 1 year subscription

Hi, I bought annual subscription plan with monthly payment a year ago( student price). It used to cost about 15.5 euro/month. But this month, I was charged 29 euro and I saw the bill for next month (January 2021), it's going to charge 30 euro. I didn't buy other products from Adobe. And I'm still a student ( I think 29 euro neither student price nor general user price) . Can anyone from Adobe tell me what happen to my account, please? Thank you advance for your help.