Mis-Sold and not allowed to cancel within cool off period

I was forced to migrate my contract and now paying double what I was. However, I was mis-sold and advised I would get 10G and 200mins. Only to find, ita split between day and nighttime data. I only get 4.5G and 200mins. I've requested cancellation and called twice within the cooling off period with no response. I will pay a cancelation fee just to get away from vodacom whom I've been with for years and years now. Apparently loyalty doesn't go both ways