Unauthorised Debits

I made an arrangement with you debit an amount of R300 in March and the remaining amount in April and this will mean I would of fully paid-up my account. Today (31-03-15) I discover that in addition to the R300 debit order that went off on 27-03-15 another two debit orders of R300 went off my bank account. I have no idea why these two R300s were debited. In March you called me to inform me that when you tried to collect on 27 Feb and there were no funds when in fact there were. I want my refund of R600.