Vodacoms unprofessionalism

I upgraded/renewed my contract last month after much hassle and back and forth with over 10 vodacom agents , I finally received a quote of R194, which I was told is the final amount for my monthly installment,( there was a yearly increase which I understand and was told that my final amount of R194 includes that increase ,even the quote I received by the agent states That it will be R194 after everything, and besides that i upgraded my contract after the 1st of april which means initially i was already paying the increase for my April bill, only later on in the month did I upgrade so how can they be charging me twice for the yearly increase ) this month vodacom deducts R208 after contacting them several times they tell me that I have to pay that extra amount for the yearly increase but I have the invoice as proof that my final amount is supposed to be R194 which they refuse to acknowledge, the agents kept transferring me to another department and did not explain anything In detail at all , and then they say it was my fault. This by far is the worst experience I've had with vodacom