36 Month contract???

I have been with Vodacom for a long time. I had a iPhone 3GS and it was giving me problems, so I called Vodacom and they said if I spend mor than R800/month every month for more than 13 months, I can get a new phone every 13 months. I then got a new phone, iPhone 4S. After 13 months it was also problematic, then I got a Samsung Galaxy S4. Brilliant phone, I kept it for the whole 24 months and want to upgrade to the new Galaxy S6 Edge. Now was told by Vodacom, beacause I did two premature upgrades in a row, I have a 36 month contract to complete before I can upgrade. I did change to to a Red Advantage contrack about a year ago, without a handset upgrade. I beleive the contract date was restted when I upgraded myt package to Red Advantage, and now I have to keep my S4 for 36 months...Never once have Vodacom told me about downsides to upgrading prematurely. Now all of sudden I hear about how the process works, they record all coversations, they can go listen to all conversations I had with Vodacom! If I had known that my contract would be changed to a 36 month contract I would have rather go buy a cheap Pep stores cellphone to complete my contract term with...