I submitted a chargeback with my credit card provider after I detected this fraudulent transaction. To that, appsumo replied back by giving a false ip report that is not related to me. I had purchased a small product from their site one year back and they are submitting those information. This fake transaction was for 600 usd and I strongly suspect there is security breach in appsumo as the purchased products are transferred to another account.
loose your credit card, call your credit agency, get new card different number, hope for a sensible resolution with appsumo now made more likely when you have turned of the taps to your bank account.