In most countries canceled subscriptions will continue to run until the expiration date. To have one end before that date you need to contact Apple and explain you need it to end immediately. However, “In Germany, Israel, South Africa, and Turkey, you can cancel a subscription made through the iTunes Store or the App Store with immediate effect." - About canceling subscriptions in Germany, Israel, South Africa, or Türkiye - Apple Support
To make a request of Apple click here --> https://getsupport.apple.com/?caller=kbase&PGF=PGF63006&category_id=SC0060&symptom_id=23208 and try to get a live representative,
or,
https://getsupport.apple.com/solutions Enter “Cancel subscription” in the search feature, enter, then on the next page scroll down to the chat or phone call option.
or:
Use this link to contact Apple for support and service --> Contact Apple Support - Apple Support Scroll down to the bottom to find a telephone number. If your country is not listed then you will have to see if there is a chat option using one of the methods above. If no support options are available you may have to just wait for the subscription to end naturally.