I Have a Problem with Cell C

good day I have a 3 cell phone contracts with Cell C store in Randburg that was approved on the 27th November 2018. we agreed that my first debit will be on the 31 Dec 2018, I expected debit on the 31 and nothing has happened. I gave the all my Documents, Bank Statement with my valid account number. I went to the to the Cell C store on the 11th Jan 2019 and I spoke to the Lady who assisted me while I was applying the contracts(shop assistance or Agent)and I wanted to confirm my account number with her that is in their system only to find out that my account was entered wrongly .she took my capitec bank card recaptured my account and I asked her to give my card back and she said "no I gave it back" when I get to work I checked if she gave it back and it wasn't in my wallet. 10 minutes later she phoned me and sent an SMS stating that I left my card in the shop. I phone cell c customer care and asked for my statement the consultant was good and helped me on the line, I asked her to confirm my account number and she gave me a different account number and I told her that this is not my account number, the sad part is that there is a some interest and now I am a bad payer, they said they tried to debit my account on the 31 and I reversed(money reversal) it, last week they told me that I changed my account as if I hacked their system. today they told me that I must pay the out standing amount of 1800 & something and I told the lady that , that was not my fault because I didn't enter my account in their system but them. need some help and advise out there all I want to know is , is that my fault or is Cell C's Fault?

please help