Been ****med by mtn mondo

On the month of 22september 2020 i took a contract with mtn mondo for data at a monthly fee of R79 then ,they made a courier of two sim card with made me a little bit sceptical because the contract i had with them over the phone was of data to my suprise one sim card was inactive and the other loaded with R100 airtime, i immediately contacted them explaining that this was not what we agreed on and the consultant said the will rectify the error ,that is when the whole nightmare started with them , the sim card that had airtime was deactivated and the other one was activated but not with data again with airtime i then made a phone call again insisting that they cancell the contract already R209 was deducted on my account on the month of november,and already they said to me i should pay R240 for cancellation at any mtn shop which i did and during the month of december they deducted another R300 for sim cards that i didnt use please kindly assist as i have been ****** by mtn mondo and on my credit score there is also a balance of 447 that they claim i owe them as well as areas of R119 i would like to know as to why are they keep on charging me for because i have paid the cancellation fees and besides that they kept on debiting me for deactivated sim cards, please kindly assist me about this matter as i think i have been ****med by Mtn mondo