Complaint of the Debit order

My name is Bahle Masinga, I upgraded to a new phone last month February which was an open network and not much was explained to me only to find that my bill shot up to R600 when I needed a break down of what I have used. they explained it to me even thor I was a bit confused but I didn't want to argue. I then called a few times to make sure and understand what will be my monthly bill and they told me it will be R757.01 and even sent me the break down sms of how it got to that amount. They just debited on my account R906 and when I ask they telling me im paying for last months contract which was February and also paying for march which I don't understand how is that possible because as far as I am concerned and from what I have gathered from them is that whatever I use for February will be billed in march and whatever I use in march will be billed the following month. I then called Cell C and spoke to Lebogang who gave me a breakdown of how it got to R906 which is totally not on what they telling me and I explained to her that I have called several times wanting to understand this open network thing and nobody ever told me what you are telling me and now you telling me that who ever sold me the phone did not explain everything to me.. I know cell c will get my complain and I want them to be aware that I will reverse the bebit order and manually pay what I know I owe and I even have an sms as proof if need be.. I am tired of Cell C doing as they please with our accounts and telling us whatever in order to get to the amount they end up debiting Sue me