"Pending" lingering after a purchase?

I've bought the $40 cartel coins a few times this month and the 2 month subscription.  After almost every purchase the pending charge will appear on my my card and ill check my card again after about 12 hours and there will be two of them, one completed and one pending.  The second charge has never gone through and does disappear after anywhere between 4 and 10 days but during that time the pending charge prevents me from using the money i should otherwise have available.  My question is, is there a way to fix or prevent it outside of just not buying anything for the game?  I've used the same card with every purchase and always received the purchased items within a few minutes.

thanks in advance and sorry if im asking this in the wrong place.