Incorrect Price Plan for Contract

I am so upset with the treatment I've received from Vodacom shop Northgate. I have been going to their store for the past few month to no avail. This year in April, I went to upgrade my contract and took an L.G Stylus which was advertised at the time for R299 on a you choose flexi 200. The consultant assisting me at the time by the name of Kgotso mistakenly gave me papers for Smart S plan but I only realized this month end. When I went back to the store to rectify this , I didn't have my I.D therefore he told me that I should come back when I have it, for a while I had not been able to do so due to commitments I had on weekends. When I finally made time to go there with my I.d one weekend which was the middle of the month , he told me he was not able to fix the matter in the middle of the month I should come back month end. After a while again I finally managed to go month end of August, he was busy on the system and told me he has fix his error and I will no longer be on a smart s plan but you choose flexi 200 which will be effect end of September which is the plan I initially wanted. I went away a happy customer finally or so I thought. Only to realize that he has put me on a you choose flexi 345- a totally different plan. I went back to the store to confront this Kgotso guy about this, suddenly he's telling me he doesn't know how to fix it, he will escalate my issue to his manager, he made a copy of my i.d and the April catalogue where my phone was initially advertised and told me to return to get feedback from Brandon his manager because he was leaving the shop therefore will no longer be employed there. With much frustration, this weekend on the 28th I went back to the store to seek feedback from Brandon the manager, turns out he had no idea about my issue and how long it has been persisting. He then called Kgotso - which turns out he **** to me he didn't go anywhere he just didn't want to be held responsible for the challenge he created in the first place. This Kgotso guy got so aggressive and defensive when the manager confronted him he didn't even want to hear anything he said or even when I tried to speak he just blocked me out and he went away. I then asked the manager what is the solution now because according to the papers I signed i'm on Smart S plan, and currently being billed on a flexi 345 yet I wanted the flexi 200, he told me that I will have to pay R2000 to go back to the flexi 200 because it's a downgrade, then I asked him then to return me to the Smart S plan, i'll live with it, he then told me that I have to pay R912 because that would be a migration. I then asked him why should I pay for a mistake that was never mine in the first place and he saw how unprofessional and aggressive his consultant was, all he could say was " I don't know maa'm, I don't know what to do anymore, perhaps you can escalate the matter and report him" I then call the Vodacom customer care line, and they can't help me either, all they could advice me was to go back to the store. What does one have to do now in such situations? I am tired of the back and forth from end of April to now end of October but no resolution.