Hi, and welcome to the Apple (user-to-user) Community.
Re: Why is apple arcade charging 15.99 : "It says it's 6.99 everywhere, in the description and when I click on the
sub button, it says "price: 6.99 per month" but I put my card info in and charge it and it tries to charge 15.99."
We are all Apple users, like yourself, in the community, so we can not speak for Apple or explain for Apple.
Also, we have no access to your accounts or details to check out what is happening with your attempted subscription. We'd like to help however, so am sharing a few thoughts below that may (or may not) help.
✽. Apple's webpages may display prices in US $ ...
so the price charged would likely look different in the different countries and in using the different currencies. (Of course, not if you are living in a country that uses US $)
Eg: Apple's iCloud + subscription prices for the different countries would give some idea of differing amounts:
iCloud+ plans and pricing - Apple Support
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✽. Apple may sometimes charge a larger amount which includes one or more other purchases from Apple as well:
ie: Multiple purchases may be grouped onto one larger charge.
See: How apps, content, and subscriptions from Apple are billed - Apple Support
You can: View your purchase history for the App Store and other Apple media services - Apple Support
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✽. If you consider the charge is a mistake on Apple's part:
You could reach out to Apple's Billing & Subscriptions Support Team for an explanation: There is a "Get support - start now" link (online chat / phone / email etc.) at the bottom of their webpage (link below):
Subscriptions and Billing - Official Apple Support
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✽. Apple also has a "bundle" price for Apple One which includes Apple Arcade.
if you already subscribe to any other subscriptions like iCloud +, Apple Music, Apple TV+, Apple Fitness +, Apple News .... The "One" price may save you money monthly. Eg: What happens to your iCloud storage when you sign up for Apple One - Apple Support
If that situation applies:
you may want more details on the "bundle", see: Bundle Apple subscriptions with Apple One - Apple Support
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✽. There may be fake emails / websites / various offers etc., that are really scams that make claim to be Apple in order to get money, account details, or personal info. You may want to check you really were subscribing to Apple Arcade: Eg: Here's Apple's webpage : Apple Arcade - Apple
If you wish: See how to:
Identify legitimate emails from the App Store or iTunes Store - Apple Support
Recognize and avoid social engineering schemes including phishing messages, phony support calls, and other scams - Apple Support
All the best :-)