Pathetic service after being a loyal customer

I took out an iPhone 6S contract on the 7th November thinking that it was 699 as that was shown on the istore website as well as the vodacom website.. I checked my bill and I am being charged 799.. I go to istore only to find out that vodacom is in charge of the billing.. I go to vodacom then they tell me to to to the istore.. Eventually I was told to call the call Centre! I called 5 times and nobody can assist me.. They tell me to go to where the deal was taken out.. I have lost all hope after being with Vodacom for years