Contract Cancelation!

I did an application with Vodacom online on 8th of April for 30G anytime and 30G night for R299. Which I called in the same day to cancel because I head there was a better offer in their branch of 40G anytime and 40G Night also for R299. The consultant who I spoke to on that day said the one I did online actually comes with an extra 30G anytime making it 60G anytime 30G night for R299, thus making it better than the previous 2. To my surprise May beginning the extra 30G is not reflecting and no one at Vodacom seems to know how to rectify that. Now when I want to cancel the contract I am being told I went over the 14 day grace period where else I was prevented by that consultant from cancelling the application same time because of an offer that doesn't seem to exist. As a first time client Vodacom I am not happy with the service I have been receiving. Cancel my contract without any extra cost as I am longer interested in using your services.