Even-though I updated payment information,
If you update your payment method or add funds to your Apple ID balance, It would take about 1 to 3 business days in order to process.
Please check again after a few days.
it’s still declined. Also, I cannot add new card too.
See -> Change, add or remove Apple ID payment methods
Change, add or remove Apple ID payment methods – Apple Support (UK)
- Add first the new card, then remove the old one.
Additional:
Optimize the range of the mobile network, see this Apple article:
If you see No Service, Searching, or SOS on your iPhone or iPad
If you see No Service, Searching, or SOS on your iPhone or iPad - Apple Support
Low Power Mode is On.
Charge the iPhone & wait until the battery is fully charged (100%).
The Low Power Mode will turned off automatically.