Apple TV is free for 3 months but still charged

If you have started your free trial to Apple TV+, then you will not be charged for that. Any subscription fees are for being subscribed after the free trial period (if you are still subscribed at that time). If you get charged during the free trial period, while having an active trial subscription, then the charge will be for something else.

Note that accessing ‘buy’ or ‘rent’ content from the iTunes Store is not included in an Apple TV+ subscription, and that content will have to be paid for separately.

Note that select third party services also offer subscription content in the Apple TV app, and accessing that will have to be paid for separately.

Note that resuming a subscription after canceling, will be at full price. Canceling before the end of the trial will forfeit the remainder of the trial.

• If you see 'apple.com/bill' on your billing statement - Apple Support. The statements for your payment method will mention the merchant (e.g. Apple), but not the product or service. You can’t assume “Apple TV+” just from that.
• View your purchase history for the App Store, iTunes Store, and other Apple media services - Apple Support. Each charge to your Apple ID account will be specified in the purchase history. Check there to see what each charge was for.
• See your subscriptions overview - Apple. Verify which active subscriptions you have on your account. For both free trials and regular subscriptions, it will list when a next charge will occur.
• If you want to cancel a subscription from Apple - Apple Support. If you see subscriptions on your account that you no longer want, then you can cancel those.

You can contact the Apple Support staff to help investigate what happened. If confirmed, then they will also assist in you making a refund request.

Note that any offers will have to be redeemed as indicated by the organization that made the offer. Just starting a subscription in any different way, will not redeem the offer.

iPhone 11 Pro Max was discontinued in 2020-10, and would not be an eligible device anymore for the offer. What product or service did you purchase, to make you eligible for an extended free trial?