Refusal to cancel old credit card

In August I was given a new BA Credit Card. ABSA refuses to cancel my old credit card on which unauthorised debit orders are still being charged, I have instructed them several times to cancel the card, by phone and email, and their answer is that as long as the debit orders arrive they cannot cancel the card. Today I was contacted by a lady from the complaints department who told me that she cannot see the debit orders - virtually accused me of lying.