Interest rate reduction

Firstly I would like to thank Nedbank for giving me the opportunity to being a home owner, and having faith in me while other banks including my personal bank didn't afford me the opportunity to have that pleasure, but with that being said, I was wondering if there is a way to request for a interest rate reduction as now I have been with Nedbank homeloans for about 5 months and the interest rate has already gone up about 3-4 times already and my fear at this point would be affordability, I do not wish to find myself in a position where I cant afford to pay my homeloan. Is the anyway Nedbank can assist in reducing the interest rate in order to reduce my monthly installment?? I know this might be a bit too much to ask for but any form of assistance would be appreciated, I would like to continue business with nedbank and in the future bring more business to Nedbank, please please please work out something for me so that I do not take too much financial strain and end up drowning in debt. I trust that my request will be evaluated, my current interest rate is 12.9% and it is starting to be a bit too much for me...