Mondly Free Trial Charge Processed After Same-Day Cancellation

Today, I signed up for the Mondly app through the Google Play Store and canceled my subscription on the same day. Although I was told during the signup process that there was a 7-day free trial, I noticed that a charge of approximately $17 was being processed on my credit card despite canceling the subscription.

I have not yet contacted Mondly customer service about this issue. I believe my subscription should have remained within the free trial period and that I should not have been charged any amount. I am requesting a full refund of the charge and confirmation that my subscription has been canceled without any further billing.