Poor Service from Nedbank Homeloans & Insurance

My home building insurance has gone up by 28% over the last 12 months and by 47% over the last 24 months. Unfortuntely I have not gone into the detail and my monthly bond and insurance debit order has been constant so I didn't notice this increase.....NEDBANK IS REFUSING TO GET BACK TO ME ON THIS..........I've been in contact with their call centre twice where they just tell me they cannot help me, I must send them a mail which they are not responding too.....