Hey guys, I am really enjoying this game, nothing to complain about here!
One thing I don't understand completely is their payment methods.

I understand that I can choose to pay for the standard 30 days and if i pay for 60/90 days right away, I will get a little discount.
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I've been thinking about paying for 180 right now, as I know I will play for this long and of course I want to save a little wherever I can!

Here's the deal though, I don't really need more than the entry subscription, as I only will play on a single server and on one character. It does however seem like that I only can pay for an entry subscription 30 days forward, where the standard (and more expensive option) have the feature spoken about above. Is this a bug or is this how it's meant to be set up?

Also, is there any price difference paying in crysta compared to credit card?

I hope one of you can answer my question, thanks!