Though as a point of interest my small UK-based B2C has seen significant abuse of card chargebacks (i.e., chargebacks issued against legitimate charges and the banks rejecting our dispute) but never a single abusive reversal under Direct Debit, even though in theory the Direct Debit has that indefinite liability attached. I suspect this is because in practice you can issue a chargeback because you didn't like the way someone sneezed and a lot of banks will uphold it while you normally have to give a valid reason to reverse a Direct Debit transaction.