Homeloan interest rate not fixed

I recently got a homeloan from Nedbank and selected the option of fixed interest for the term of the homeloan. However, not even two weeks in to my new home and i get a notification that my interest rate has been increased. The address on my home owners insurance is also incorrect, despite me sending a request for the address to be corrected. I need this all rectified immediately. It is unacceptable to have to check these small details for such a large institution.