The error is not with your financial institution, it is with SE. My gf was trying to pay for another 180 days, she has plenty of money in her account, she still received the 406 error. She then tried her Credit Card, also with more than enough funds, and once again 406. The customer service is inefficient any way you look at it. They are quick to blame you instead of looking at maybe there is an issue with our system, such as a glitch. I am curious if anyone else used a Master Card as their payment and came up with the 406.

I have no clue why SE wont let us use a PayPal account. If I were to put money on it, I would bet that no community rep or anyone from the dev team will comment on this issue, in any of the threads regarding it.