ShortsWave Stop Charging My Bank Account

I live in the USA and I am being repeatedly charged by ShortsWave even though the app shows that I do not have an account to cancel or unsubscribe from. On 09/14, 09/21 and again today, a payment of $17.99 was taken from my debit card under the name SHORTWAVE SINGAPORE SG. When I open the ShortsWave app, it states that I have no account to unsubscribe or cancel, so I have no way to stop these charges from their side. I contacted ShortsWave about this situation but received no effective response and the charges have continued, which is shocking and unacceptable for me. I am planning to contact my bank to block or dispute these transactions if they are not stopped immediately. I request that ShortsWave urgently identify how my card information is being used, cancel any subscription or billing linked to my card, stop all future charges, and refund the unauthorized payments of $17.99 taken on 09/14, 09/21 and today.