Contract ended November, Debit order end Feb?

My contract was cancelled and ended end November. Last debit order went off 27 November 2014. I phoned several times to confirm is all done with R0 balance and was assured by couple of people that account is closed and R0 balance. 3 months later 28 February 2015 a debit order goes off my account. Firstly customer care said that they do not debit on weekends. And then he tells me it was for the usage of November. I paid end November my last debit order!!! I want my money refunded back to me today!!! Now other debit orders will not go off because I did not budget for this.<br> Not even a invoice or statement was sent to me about this. 2 weeks ago I received a R0 balance statement and even phone to confirm all is done and closed.