No warning into terms of buying a bundle

Hi telkom i am very dissatisfied with the way you guys sell data bundles on your *180# service as i purchased a internet starter pack data bundle for 6 gig that i needed only to find out after the purchase that i will be getting 512mb for the next 12 months... no where was this made known to me before purchase and thats not what i wanted i have been a telkom customer for a few years now and never encountered such a problem as this i would like a refund or the complete 6 gigs made available to me as this is unacceptable as i was not informed that it was a 12 month bundle thanks