Apple Store Missing Refund Fee

I purchased an EnglishCentral Premium membership on September 1, 2023. Unfortunately, the membership I purchased through the App Store did not activate, so I decided to cancel it. Fortunately, my request was approved, and I received a refund on September 3, 2023. However, I discovered that the amount refunded was less than what I had originally paid. This experience has left me very dissatisfied, and it is frustrating that I did not receive a full refund for a service that I was unable to use. It has also eroded my confidence in making future App Store purchases. In retrospect, I would advise others to be cautious when making similar purchases, as my experience with EnglishCentral's Premium subscription left me with a negative impression of App Store purchases in general.