Mondo misleads on behalf of Vodacom, and Vodacom doesn't fix it

I sign-up for a contract telephonically. The deal was some amount of Rand airtime, as well as 2GB 'incentive' data, which was a great deal. When my contracted started, I only got the rand airtime. When I phoned Vodacom about this, they said "this is what we have on record", and they can't help me with my query. I asked whether we can listen to the telephonic recording again, and they said they can't help me and I have to phone another company, Mondo. I couldn't reach Mondo. Why do I have to follow up with Mondo, while I have a contract with Vodacom? It's not my responsibility if Mondo lies on behalf of Vodacom. I emailed to cancel my contract with Vodacom, and responses are slow and ineffective. Vodacom, Mondo, please fix your mistakes.