Unsatisfactory customer service and non-performance by Vodacom

I have been contacted by an agent of Vodacom in February 2019 informing me that one of my 3 contracts I have with them is due for an upgrade. The contract is due to expire during May 2019. I discussed a certain package they were offering and was told they would send me a new handset I had chosen. After about a week the handset never arrived. I queried Vodacom, who said they had run out of stock. I then informed them that I prefer the contract to revert to its previous terms, that is a tablet I had received in 2017 with monthly 2GIG data. The agent I spoke to agreed and said, as of March 2019 I would receive my 2GIG data. This did not happen and again in April 2019, I did not receive my 2GIG data. I phoned Vodacom to query this and was told I am on a new contract. I asked them: how can that be, as I never received a handset. I am now referred from pillar to post when I query this on the customer care number, if and when I can get through, due to high call volumes. My request to the agent to cancel the upgrade, which he agreed (I told him I shall see what other handsets become available in March or April 2019, before I decide on the upgrade), ought to have been recorded. My question to Vodacom is, since they have not performed on the upgrade request, surely due to non-performance, I am entitled to cancel the upgrade. I cannot get anyone at Vodacom to assist me on this aspect. In the meantime I have to pay the new 24 month contract without a handset?!....