Vodacom in breach of contract

I upgraded two contracts with Vodacom on 25 April 2021. (The call was recorded) The sales person was Zahieer. The agreement was that when I upgraded, I would receive a 500.00 voucher to spend at Woolworths, Takealot or Pick n Pay. The voucher would be sent to me via email within the week. In the 2½ months of dispute, i have phoned Vodacom more than 20 times, with no response and no assistance whatsoever. I phoned once again yesterday and documented what happened:

I phoned *** (i was told to phone this number the day before). I spoke to Lindiwe. The reception was so bad that I had no option but to cut the call.

I phoned the same number again and spoke to Sizwe, who said that I was through to the wrong department and i must phone the cancellation department on ***

I phoned *** and spoke to Lefa who said that she can't help me and I must phone ***.

I phoned *** and spoke to Bongi that she could see the upgrade, but was cut off from Bongi

I phoned *** again and spoke to Brian, who said that I must speak to the backorder/after sales department, so that they can track the order. I must phone ***

I phoned *** and spoke to Silindile who said that she couldn't help me because I was at the wrong department. She told me to phone the outsourcing company on *** I phoned the outsourcing department on ***and spoke to Veronica who said that she could not help me because Vodacom issues the vouchers, but that she would escalate the issue but I should phone Vodacom for the voucher

I didn't have the energy to start phoning Vodacom all over again

Please could you tell me where to go from here. Clearly Vodacom are in breach of their contract with me, and they have no intention of assisting me in any way. After promises of phoning me back, no one has phoned, no one has assisted, I can't cancel the contracts and I have no voucher. Can you help?? Best regards Terry van der Peet