How to resolve 'There is an issue with your payment method' error when changing iTunes country?

Hi. As the title says, I can't change my iTunes country. I tried everything, like providing a valid payment method for the new country, double checking all of the details, removed the previous ones, left my family sharing group and signed out of my iCloud completely. I even tried changing the country on a computer. However it keeps giving error: There is an issue with your payment method. And on the computer, the error is: We've ran into a problem.

[Re-Titled by Moderator]