Nedbank inconvenience

I have been banking with Nedbank since I was a child and my mother opened the account for me. I took out a loan with them and paid very well. I changed jobs and informed them that I won't be able to pay for last month as I am getting my first salary this month only. I made arrangements them to pay back the installment over 3 months. When I got paid they deducted the amount we agreed to and the normal installment twice. I called in to find out what happened because we agreed and the consultant I spoke to told me I would not be debited twice yet I was plus the amount we agreed to. They told me I will only get a refund in 5 days which is very long because I need the money this is very inconvenient for me. I need this to be sorted out asap please