Contract issue

I would like to migrate to a new package. The straight up 200 top up. My current contract is the smartchat 1 gig. I am not happy with it as I did not get what I was promised. The agent said that I would be able to add a voice bundle to my contract at an additional charge of R75 but that she could only do this when my contract was active which was in July. In July nothing happened and so I called cell c, only to be told that the voice bundles has been discontinued. The only reason I took this contract was that I could add more voice. Now I have been told that I would have to pay a migration fee to change my package. I want my contract changed and I do not want to pay a migration fee as this is the fault of your misleading call centre agents. I did not get what I asked for so this contract is now useless to me. Please change my contract immediately.