Vodacom **********ly bills customer for free bnfts

Being unhappy with Vodacom being 1 of the most expensive communication service providers in the country, I was cancelling my contract (Been a Vodacom customer since 1997) in 2014. The cancellation department is authorized to issue free VAS at no cost to the customer. 1 of the benefits that I was to receive was 1GB data for 24 months should I choose to stay with Vodacom. I have this in writing from Customer services department, along with the contract. After 12 months, I've noticed my bill being drastically high and Vodacom charging me R1 per mb, and I was not issued with the 1GB. Upon investigation, the CSC advises that they have incorrectly billed me and will credit me as well as allocate the 1GB data. This was resolved in July. Yet again, same issue pops up. This time, 'Trade Partner' handle the complaint and tells me that it was valid for 12 months only. I have forwarded Trade Partner my communication with Vodacom