Cell C ******** over R22k on a R150.00 sim only contract. Worst company ever

Cell C ******** over R22k on a sim only contract of R150.00. i took an open line data 10gb contract with them after they called me and offered, i asked them to put a limit which they ask me to call in when i received the sim card to set the limit, after i received a sim card they called me to offer another contract, i told them i just received a contract 10gb data even requested them to put a limit, the agent assured me the limit was set to R160.00, only to find they saying the limit was not set when they started billing me ridiculous amounts of money, and the investigation can't find the recording where the limit was set, they saying am liable. Honestly i can't afford to pay for their mistakes as i have always paid for them, they have canceled my contract several times without my consent because in their system someone who is not me requested.