Early upgrade (Under false presences)

I was contacted by Cell C and were told that I qualify for an early upgrade. I went to Cell C Menlyn and the person that helped me confirmed that I can early upgrade. So I went for the option of early upgrade. One of my questions was what the catch is and the answer was nothing. I asked what happens with my contract that I currently have and was going to upgrade and he explained that I will get my new phone a LG G4 and still pay my current package which is a 400min package and then from April 2015 the upgraded contracted will start which I will than pay for the upgrade which I took as a 200 min contract. Today when I checked my minutes I only have 200 minutes were I was supposed to have 400min. I went back to the Menlyn shop and they told me sorry they can't help me after giving me a answer which wasn't satisfying at all. I phoned Cell C and they told me I am on a 200min package and were still going to pay an additional 169 for 4 months because all of the sudden I \migrated"and still have to pay of my old phone.<br> <br> If I knew this was the case I would have never went for the so called early upgrade. No one told me or informed me. Please assist as this was and is completely unfair"""