After downgrading my iCloud storage purchase,AppStore keeps charging my credit card,Why?

I want to know why you keep charging my credit card ¥130 yen monthly,for the last 6 months after I downgraded my storage plan.You keep charging and I’m not using it,I even deleted my card info from my profile at the AppStore,but to no avail,and you don’t give me access to something I’m paying for !!! I have photos to prove in my phone!!!!Fix this ASAP or I’m going public on Twitter Japan