I have a problem with an app in the app store

Hello. I recently activated a free week of Chai Premium (an ai chatting app) I stopped using it, but because I forgot to cancel, I was charged a year's worth of premium. I requested a refund twice through Apple Support, but they denied it for no apparent reason. I emailed Chai's email address, but they also directed me to Apple. I don't know what to do now, so I'm writing here as a last resort. What should I do, what steps should I take, and can I get my money back? Thank you.