Migrants to IJ, 2007

the best thing to do would be to call the credit card company, explain the circumstances, and tell them not to accept any more charges from LJ/6A.

Not possible, I'm afraid. Once authorised, payments on a debit or credit card cannot be cancelled except by cancelling the card altogether.

You have to wait until the transaction appears on your credit card statement and then contact the credit card disputes line to get the payment claimed back. And be prepared to do the same thing the next month, and the next, until eventually LJ gives up and stops taking it.