Can’t add payment method

I have replaced my phone and moved country since my last purchase on appstore.

I struggle to add any payment methods to delivery and payment tab ( it is all blank). I have searched in this forum what is the solution for this error without any luck.

As a probable root cause, I matched my billing address to Australia, same as my credit card issued.

However I am keep getting error messages as below:

Payment information could not be updated.

Invalid Credit Card Security Code.

I tried multiple cards with no luck. Even added my mobile as an alternative payment method - after receiving the verification code via sms this error message pops up -

 Invalid Credit Card Security Code.

Any thoughts?

Thanks!