Thank you for reaching out with your concerns. I'm really sorry that you've been charged unexpectedly, we can certainly take a look at this for you.
It sounds like you may have a time-limited discount which has come to an end, or an offer price that has finished. However, I'd like to take a look at your account to get to the bottom of this for you. I'll send you a private message now so we can clear account security, please head to the purple envelope in the top right corner to respond.