So many additionals in that sentence... Do you mean 12.95 plus an additional 1.00 for an extra character, and THEN an additional 12.95 to add up to ~27.00? From reading that, it sounds like you said youre paying the 12.95, plus 13.95, plus 27.00, which if you are paying for 2 accounts and just reactivated them (before may 1st or 2nd) then they both get charged twice for 2 months worth of fees.
Regardless, have you been paying for a long time? If you recently reactivated your account (before May 1st or 2nd) you will get charged twice because PoL billing blows and they charge all CC's in the world at the same time instead of by per 30 days.
Also, yes, check to make sure a friend/family member didnt take it to pay their own FFXI bills. I dont believe anyone hacking your ffxi account could take your CC number, because not only can PoL give out that info, its incomplete on the CC panel. And I find it hard to believe someone hacked into your CC account just to play FFXI, lol.
After all thats checked, I think its safe to assume its a mistake on SE's side. Its happened before.