Payment method declined for Apple TV ONLY

Payment methods that you can use with your Apple ID - Apple Support

If your payment method is declined in the App Store or iTunes Store - Apple Support

Your payment method must be issued in the same country as what your Apple ID account is set to.

Your payment method must allow pre-authorization, so that any future purchase can be charged to that without a manual bank contact procedure.

Subscriptions require a payment method that supports automatic and periodical charges.

Not all debit cards may qualify, but those might still be useable to add funds to your Apple ID account. Add money to your Apple Account balance - Apple Support

On/through what device and model are your trying to watch Apple TV/Apple TV+?

it is the Apple TV+ I’m trying to subscribe.

Ok. Excellent. Redeem the offer on you new qualifying Apple device (iPhone), not on a different device. Else the offer may not apply.

Read here how to redeem: Apple TV+ offer - Apple (①)

Read here about the conditions: Apple TV+ offer - Terms and conditions - Apple

Read here if you have trouble redeeming: If you can't redeem your promotion for an Apple subscription - Apple Support

↳ Step 5 says to contact Apple if the prior steps didn’t bring a solution. They can assist.

as I bought a new iPhone I get 3 month subscription for free.

If you didn’t have a free trail to this before, then you are eligible for a 3 months free trial to Apple TV+, when you recently bought a qualifying Apple device (such as a new iPhone). You will need to redeem it in the described way (see above ①).

I managed to do it for the Game Center,

Game Center is a free (administrative) service. Did you perhaps mean Apple Arcade (1m free trial, then 4.99/m)?

I’m able to pay anywhere with Apple Pay. So, my wallet is working

Apple Pay is an electronic contactless method for payments in stores (mostly). It doesn’t have to be set up as Apple ID payment method, although it can be in some countries. It is a separate setup from the former. E.g., one could have a debit card for Apple Pay, but a credit card as Apple ID payment method.

Add a payment method to your Apple ID - Apple Support

but when I try to subscribe to tv+ it says the payment method was declined

All purchases of digital goods and services are billed the same way. If you can buy a paid app, or rent a movie, or subscribe to anything that uses billing through Apple, then Apple TV+ should succeed in the same way.

See here for more information, and how to proceed: If your payment method is declined in the App Store or iTunes Store - Apple Support

• If you still need help with the declined payment method after that, then contact the Apple Support staff.