Gather up all your evidence. Call your credit card's issuing bank. Ask to speak to the fraud department. Clearly explain that although you may previously have authorized some charges, you did not sign up for any service allowing OptionsXO to make unlimited withdrawals from your card. Show them which withdrawals are unauthorized and ask how to file a chargeback complaint.
If the bank delays taking immediate action, also ask them to cancel the current card and issue a new one. At least this will save you from having additional charges placed.