Refusal of accessing credit card information

I had a problem like this for about a month or so and I did contact Mojang about this and they said that it was more my browser.
They told me to clear cookies/cache. If that didn't work, try changing your browser and/or changing to a different computer or device. I did all of it and nothing worked and it is still the same.
I think it was more of the account because another friend bought another month just fine and did not have my issue. Any help or am I doomed and I am no longer able to buy any more months of MC realms?