Cancellation of my contract with vodacom

I have a contract with vodacom been trying to cancel my contract, i have spoken to 8 different consultants including the teamleader and they have all sang the song that they will take ownership and call me back because when they try to cancel on their system its giving them an error message and there is nothing they can do about it. They have told me, the teamleader will need to authorise but it seems like they are not trustworthy because they cant keep their promises