Appalling service and misrepresentation from MTN

On 3 August 2023 I went into an MTN store and requested to upgrade my cell phone contract from the MTN Made-for-Business M (medium package with 6.5GB data + Anytime SMS + Anytime minutes for R349/month) to the Made-for-Business L (large package with 23GB data + 1000 minutes + 200 SMSs for R619/month). The new package was confirmed. When MTN loaded the new contract, however, they only provisioned 3GB instead of the full 23GB data. I immediately went back into the store where I did the upgrade and the consultant confirmed that I should have been provisioned 23GB of data. I then logged a query. Over the next 8 weeks I visited the store on multiple occasions and sent numerous follow-up emails to no avail. I then visited an MTN Direct store and made a complaint to the manager. He tried to assist me and escalated my complaint. I followed up with him daily also to no avail. I finally received an email from MTN telling me that the reason I am only receiving 3GB data is because I signed up for a package with promotional bundles. However, when I migrated the number from the Made-for-Business M to the Made-for-Business L package the promotional bundles fall away, and I only receive the bundles that are included in the package. This was never explained to me at the time of the upgrade. It was completely misrepresented to me. I would not have agreed to upgrade from 6.5GB data for R349 to 3GB data for R619. What sane person would agree to that? I have asked what needs to happen to have the promo bundles reinstated but have had no response. When going back to check the contract and the invoices, neither document details the contents of the package. The contract states a price value only and the invoice states the package name with no details of what that includes. This makes it very difficult to prove what was agreed to. I only have a copy of the advertised package from the brochure, which is what I requested and was led to believe I had purchased.