Incorrect Annual Charge Instead of Monthly Subscription with duolingo

I am writing to address an urgent issue regarding my recent subscription charge. On the 29 of September, I opted for the monthly subscription plan for Duolingo. However, I noticed that my account has been charged for an entire year instead of the monthly payment option I selected. This discrepancy has caused significant inconvenience, as the annual charge has depleted my funds for this month. I have attempted to resolve this matter through various channels, including email and duolingos online chat support, but have yet to receive a satisfactory response.

I really hope you can help me out with this problem?

Best regards Helene