Vodacom in breach of their Contract

I upgraded two 24 month Vodacom contracts in April 2021. Part of the deal (the call was recorded) was that I would receive a 500.00 voucher to us at ww, pnp or takealot. Well, the voucher has never materialized and after 5 phone calls, and 3 months later, I am no further with this issue than I was in April. Everyone says its not their department to deal with the problem, and someone will phone me back. To date, no phone calls and no voucher. But Vodacom are in breach of their contract so the next thing to do for me is cancel the contracts after I've been with them for about 20 years, and find another service provider, unless Vodacom come to the party!! The sales person was Zahieer