I'm so disappointed with Nedbank home loans

I am so disappointed with the service I'm receiving from Ned Bank home loans, I app**** to have my interest rate fixed for the next 3 years seeing that I will have a problem with my installments if the interest rate keeps on rising, form were sent for me to complete I did that and send back, I was denied for the fixed rate reasons stated was affordability, I fowaded my issue to the complaints department, the a lady called Lizzy nkanyane called me back saying my application for a fixed rate was declined due to affordability, I explained to her that my home loan installment increased 4 times form last year to this year no one was looking at my affordability that time, u haven't missed a payment on my bond for the past 3 years, I'm trying to prevent that from happening but requesting a fixed rate but not one is helping me, the service I'm getting from them is very bad, they are not helping me as a clients