loan dept dispute

I'm disgusted at the service I've received from the loans dept... I requested a debit order date change as I had changed jobs and as a result my salary date had changed, they provided me with one,however when i checked my bank statement,my installment had increased from R299 to R384. When i questioned this i was told it's because I requested a debit order date change. I asked ok if that is so kindly provide me with proof in my loan agreement, whereby it states I would be subject to an increase in my installment should i change my debit order date,l.No one provided me with proof till today. Instead I had Nozipho Thwala copy and paste, what their colleague had told me about being subject to an increase in my installment,instead of addressing my issue. I warned these colleagues that I'm fed up with their service and would be taking it further and requested to speak with a manager. What do i get?! Melissa Williams sending me an email today,not addressing my question, instead telling me that a request has been put through to add another month to my loan to reduce my installment,which is not what I wanted. I just wanted someone to help me, I work in Customer Service and I know how important it is to value your customer,but this service I've received is totally off putting and it makes me wonder, how many more customers are being treated this way. The thing that's also disgusting is the fact that it takes them a week to even respond to your query.