Debit Order

I had a 24 month contract with Cell C, it expired in February 2015, I called cell c to cancell the contract in February, and I was told they will deduct the full amount in February, then R56.50 will be deducted in March and it will be my last payment because i only cancelled the contract late in Feb, and I was assured that the contract has been cancelled, the consultant I spoke with asked if I wanted to keep the number and i told her No, to my suprise, a Debit order of R56.50 went off my Absa account last night & Absa bank charged me another R8.00 for the Debit order, I don't know what the money is for, I tried calling Cell customer service this morning, but they keep disconnecting me,