Switching from regular premium to student premium.

[Logic2]

Hi there, I used student premium all last year and over the summer I forgot to renew my eligibility as a student for my next year. A few days ago I was billed the full £10, so I renewed my eligibility on UNIDAYS. I read that you can instantly have student premium go on from the next billing date so I went through the student premium link, and when I go to redeem my student discount, I get an error message saying that my student credentials are associated with another account? Which they aren't, I'm simply just trying to reauthorise my student credentials on my only account I've ever had/used. If anyone could tell me if I've gone wrong somewhere? Or whether the discount has been applied regardless, I'd really appreciate it, thank you!