My contribution in offer not the same as one debit

I have to express my discontent over the service I got with discovery. It's unsatisfactory. <br> <br> I joined Discovery this year and got an offer letter which stated that my monthly contributions is R435 monthly. It came to my surprise that a premium amounting to R1248 was attempted to be debited from my acc to on 15 March 2016. When I called discovery I spoke to Candice ( what a rude lady!!!) who informed me that there has been an error in my offer letter and the correct amount is R1248 in their system. <br> <br> I was not informed about the change in my contribution, I was never made aware of it until I called. I would like to be provided with reasons for changing it and for not informing me. The offer letter does not reflect what is in the system. And I never signed anything which required me to pay R1248 and I ask myself who authorized you to debit that amount without my acceptance through signature. I am unemployed and cannot afford such a premium. I had provided an affidavit in my application that stated that I get R1000 monthly from my daughter as assistance, so how am I supposed to afford R1248?<br> <br> Where is customer service in that ? My customer rights were violated.