Nedbank digging their hands into your bank account

I was on maternity leave for 4 months from 1 Aug 2014 to 30 Nov 2014 and as a result my personal loan with Nedbank went into arrears.I was able to start paying them my installment of R2531.25 again end Jan 2015.I then made an arrangement with Nedbank to pay my installment of R2531.25 starting 28/02/2015 for 3 months.I have an sms from them confirming the arrangement reading:\Nedbank Personal loans arrangement confirmation: Payment of R2531.25 by debit order starting from 28/02/2015 for 3 momths.***".They deducted the R2531.25 today"