bad customer servve

Good day i have been banking with Nedbank for Few months n in October i took a personnel loan with them,the first installment was supposed to be on the 31 december 2015 as per our agreement.on the last week of November i received an sms from nedbank stating that they will be debiting from my account.i called the customer servie department to explain that there wont be available funds in my account as i will only be paid on the 31 December 2015.the lady said that wont be a problem as the sms was send for people who will be getting paid on that day.on the 28 December an amount of R 766.63 then i called the call center to ask why they debited from my account 3 days before the date we agreed on and what will happen now on the remaining balance bcs i was only getting paid on the 31.The guy told me he dnt know what happened and that the next debit will only be debited on the 31 January 2016 and the balance will be added to my installment the 31 December an amount of R288.26 was again debited from my account,today on the 5 January 2015 another amount of R 1409.08 was debited to my account called the call center to find out why nedbank has been debiting on my account on the dates that