Fast Deals Today — multiple withdrawals

I have had this company withdrawal the same amount twice on one bank card and when after receiving a new card had the same charge be withdrawn again. I have now had to go to the bank and fully change all my account numbers and not just my debit card! Absolutely confused as to how they keep doing this, feel as if they must have hacked a company and stole peoples banking information, not sure as to what company or how many people were actually affected by this.