Just thought I'd add my experience. Hopefully someday they'll stop pretending it's not their fault and fix this.
I keep getting error 406.
I already called my credit card company who said they could see the $1 charge getting cancelled by the merchant. There was nothing wrong with my card nor was there any blacklist against SE.
I have definitely waited more than 24 hours. But since support won't tell me, I don't know if I'm on 30 days block. How many times is "too many" to try using my card? 4? 8?
I tried buying Crysta using my credit card: fail
buying Crysta using ultimate pay>credit card : fail
buying Crysta using ultimate pay>paypal : fail

Honestly why is Crysta even an option? Why does it even exist?
All that's left for me to try is buying the time card. But for the same amount of days I want to add (180 days), I'm paying $12 more.

If I can buy multiple items on Amazon using different credit cards and addresses, why is it so hard for me to buy 1 item off SE? I don't get it. I'm practically throwing money at you! TAKE IT ;_;