Unsatisfied customer

Early in December 2017 I was called by a Mr price mobile call centre asking if I was interested in taking out a tablet contract for 24 months at only R99 per month. I asked them to call me back the next day after 4pm because I was busy at that moment. When they called me back the next day I was explained about how the contract works and the terms and conditions of the contract,the lady explained that the first payment of R99 will be debited only in January on the date I choose. I agreed to it and told her it must be debited on the 15th January she said that would not be a problem.I kept on asking is the first payment really only in January and she said yes mam you will only be debited in January. On Saturday the 30th of December 2017 I received a notification from the bank about a unpaid debit order of R199 for Mr price mobile,i could not understand why this was happening knowing that my first payment will only be in January 2018 and why has it gone from R99 to R199? I immediately called the call centre and explained what had just happened and then I was told that the R199 was a once off sim connection fee,i told the lady but that was not explained to me the day I was asked to take the contract because if it was I was either not going to take the contract or I would have made sure that I had funds in my account for that debit order because now I have to pay R150 for an unpaid debit order which I feel is very unfair seeing that all of this was never explained to me,she then said there is nothing she can do to reverse it. I told her that their calls are being recorded and if they listen to my recordings they would hear that it was never explained to me,her answer to me was mam i am explaining it to you now. I got really upset because I feel this is very unfair and unprofessional. Please help.