Promising to deliver by failing to do so

When upgrading in July 2014, I opted for the Smart M contract but I was not happy with the amount of data and minutes that the contract had. i.e. 120 minutes, 500 mb (plus 250 extra on special) plus free sms's. After negotiating with the retention department it was agreed that I would receive the normal smart M contract PLUS 1 extra gig per month PLUS 100 free vodacom to vodacom minutes all for the smart M price of R549.00 per month. Months later I realized that they had only given me the 1 gig as a once off and not ongoing,so when i thought I was getting 1 gig extra every month I was in fact not and thus my monthly bills were way above the R549.00 that I agreed on, as I was being charged higher data rates due to usage. I called Vodacom on 27 Jan '15 to fix this problem and was told that a supervisor would investigate and get back to me. I am still waiting to hear from this supervisor. I called again 2 weeks later & spoke to Brilliant who confirmed that it was fixed and that I would receive my 1 gig every month which I did the first month, but it still only happened as a once off. I am tired of this now, and for the first time in 20 years I want to leave Vodacom! It is unacceptable