Impulse App Charged After Trial Canceled on Google Play

I signed up for a trial subscription of the Impulse app through the Google Play Store and realized after using it once that it was not what I was looking for. Right after signing up for the trial, I unsubscribed and canceled the subscription through Google Play. Despite this, my account was charged 29.99 on May 1st. I contacted Impulse support by email and only received automated responses, and I was unable to reach a live agent even though I also tried calling. I find it unfair to be charged after canceling the trial immediately, and I believe this payment was taken in error. I kindly request a full refund of the 29.99 that was charged after I had already unsubscribed from the trial, and I would like written confirmation that my subscription is fully canceled and that no further charges will be made to my account.