Misrepresentation of Product Sold

I purchased an LG G flex2 cellphone from Vodacom which was said to have certain features such as 32gigs onboard memory. This feature was also stipulated in the contract that I signed. 3 weeks later I discovered that the phone only had 16gig onboard memory. I notified vodacom and was told I'd be called to resolve the problem. This never happened. Its now been 2 months since the incident. I've contacted them several times to no avail. All the while long I've been paying full amount every month for a phone that is lesser than the expected phone. I've incurred many costs calling them and going to vodacom and still this is not resolved. They offered me a 16gig memory card but this is not fair because it means that once that memory card is full, I must still purchase an even larger sizes memory card.