Paid subscription through App Store didn't gave me access to the Pro version of the app

After purchasing the pro version of an app, I still had the free version of that app. After contacting them by ONLY emails, they finally responded, but that entire month I had paid for, my account never updated/upgraded to its pro version. And was also spent just literally emailing them the same exact information, like explaining the situation, i dont know how many times I sent several receipts of that purchase, receipts from Apple, my email, and even my card, including screenshots of when purchasing the pro version, every other day, and still lost the entire month and still have no result, the just kept emailing me back saying they can’t find what they needed( some ID number or something, even though it was right on the screenshots)?

[Re-Titled by Moderator]