Duolingo Charged Me After Trial Ended Without Notification

Duolingo promised to notify me when the trial period was ending, but I never received any notification. Despite this, and even though I canceled the trial before it expired, Apple still charged me when I accepted the trial offer. I was not informed about the upcoming charge, which goes against what was promised. I am requesting a refund for the amount charged, as this was not communicated properly and the trial was canceled in time. This lack of notification is frustrating, and I expect the fee to be returned promptly.