False promotional contract information - now I only receive half the data I am paying for as agreed per contract

I was contacted by Vodacom on 25 March 2019 to sell me a promotional upgrade on my data package on an existing router. I asked and confirmed 3 times, with the vodacom sales person confirming and repeating that for the monthly amount of R349 I will receive 20GB anytime data plus 20 GB night owl data every month and on this promotion I will receive an "additional 20GB anytime data every month for 24 months". They confirmed 3 times that it means 40 GB anytime data plus 20 GB night owl data every month for 24 month for R349 a month and that the change will automatically occur 1 April 2019. It is 1 April 2019 today, and my balance only shows 20 GB anytime and 20 GB night owl. Where is my additional 20 GB data? I would not have agreed to the deal if it was only 20 GB anytime and 20 GB night owl data. The conversation is recorded. I would like this to be corrected and my 40 GB anytime data plus 20 GB nightowl to be awarded.