Unauthorised debit from my account

A debit order of R704 was made from my account. Nobody informed me that this amount would be debited. I terminated my membership on the 31st of July. On the 20th of July, My employer informed me that I owed Bankmed R1335 and that it would be debited from my account. That was done. So on the 22 August, a debit order of R704 was made from my account. Bankmed didn't notify me or get authorisation as to what the debit order is ,according to my understanding my membership is terminated and I do not owe them anything. I am extremely angry.