I am not sure if this thread is up to date, but since I am on the same boat, I'll post here anyway. I've been having the same problem. Weird thing about it is that I used my credit card for buying stuff before 2013 and after. All of a sudden and for some reason I can't do it anymore. I tried accessing my account so I could change info, but this thing is a mess. I've possibly messed things up ( I created my account so long ago I didn't even know what info I was giving), also it doesn't help that my billing address and physical addresses are different.
It was working however on more than one occasions. And now it is impossible to change region, info due to the fact that I no longer have in my possession the number I had given.