Shortswave Continued Charging After Cancellation Request - No Response

I had a subscription with Shortswave that I started in May. When I decided to cancel, I first tried to cancel it through the app, but my subscription was not visible in my Google Play subscription history and I could not complete the cancellation there. Because of that, I requested cancellation via email on June 16. Despite this, charges continued after that date, and I did not receive any response from Shortswave to my cancellation request. Today I sent a second email, but still have not received any reply. I am requesting a refund of all charges made on and after June 16, confirmation that my subscription has been cancelled, and a clear assurance that there will be no future charges to my account.