Worst Service ever

I am flabbergasted with the service that I just received from MTN, I upgranded my contract 2 months ago when I took a package that I need to pay R359p/m, my first installment was R447.99 which I thought maybe there's a pro-rata added, then this month it's R663.71. I then called the call center and spoke to Patricia Mabaso who tried to explain why the amounts are not the same. She said unfortunately what's advertised is excluding vat, meaning the R359 I saw is excl which was never explained by the store and have been with MTN for more than 15years it's the first time to hear such hense the R447.99 and the R663.71 includes the pro-rata, she then transferred me to Thandeka Shibe MTN Direct to down grade my contact as I explained to the store that I don't want to pay anything more than R400, instaead Thandeka just said she can't help me instead I must go back to CS Dept, when I told her I am from there, she just said then I must go back to the store, can someone who knows what is what there to fix this matter.