I can't buy Democracy 3 DLC from mac apple store?!

I bought democracy 3 from the mac apple store and wanted to buy two or three DLC.
When I attempted this is comes up with a pop up saying I need to log in. I log in, then another pop up, I need to type my password again. I type my password again, and then it comes up with ANOTHER pop up saying I need to log in AGAIN. After doing this it says my password is incorrect or my account cannot be found.
I have $37 on my apple account
I changed my password.
Ive reinstalled the game 50 times.
Ive done everything possible and all I wanted was to buy the DLC.
Can anyone help???