Medical aid premium increased without notifications

I am a 71 year old pensioner who started medical aid with Liberty in 2014. The scheme was then taken over by Bonitas. My premium is R1475. My broker Clodin Nagfaal asked for proof of income in September 2017 and all was provided. Clodin confirmed all was in order so I was shocked in Jan 2018 when I was debited R3900.00. The same was done in Feb 2018. I cannot afford this. I called in and for asked for assistance as this was an error on the side of the medical aid but have got no positive feedback as this should be something that the medical aid fixes. I cannot afford R3900. Please assist. Thanks