Ridiculous increase without notice

I have been a policy holder for insurance with Hollard, I have never gotten any notice that my premiums could be changed or what percentage will be used for that increase should it happen. To my surprise when my debit when through this month 01 Dec 2015, it had increased by R250.00, can this be rectified and my account be refunded? This is ridiculous, you can't just increase premiums without prior notice or explanation for that matter, I believed Hollard was a reputable company until this happened, I have since lost faith.