SIXADS Shopify app charging despite cancelling few days after it failed to provide services

Would just like to ask if anyone in this community has ever installed SixAds shopify app. We tried it out for a couple of days, its marketing campaign failed to register even we put in a budget of $40± . we then emailed their customer service numerous amount of time but to no avail. After we chose to unsubscribe from their plan and delete the app, only did their customer service representative started emailing us, asking if we had any problems with their services. Few days later, we got a charge from Shopify saying we had to pay for SixAd app services even though we gained nothing but wasted time and effort from installing their app. If anyone had the same experiences/ have been in the same situation, please comment below if you’d managed to resolve the issue.