Unsatisfied with FNB Home loans terms review process

I app**** for a loan term extension with FNB Home Loans and I'm not happy with their process. When you call the Home loans agent they tell you its possible to apply for an extension, which is calculated based on your outstanding balance. I completed the application form for the extension, also mentioned that I received an interest rate discount (prime - 0.6), and sent it to the loan terms people, and they declined, saying that my repayment would increase. I responded to them, saying that I recently received a new interest rate of prime 11.75 - 0.6 = 11.15%, which decreased from prime 11.75 + 0.6 = 12.35%, I also mentioned that I would like to increase the term to 30 years calculated on my outstanding loan payment, so how can the repayment increase? They don't respond to my mail; they should at least share a proper explanation for their declined response, it's frustrating, and I'm highly disappointed because you can't even call them. The call center tells you it's possible, and the loan terms people don't provide a good service with their process.