Incorrect Billing

I was called by an consultant about a sim card deal only for R99 p/m for 20GB, which was great. Of course I accepted. Upon receiving my sim cards on the 28th June there was 3 sim-cards in the pack and i received a bill for R99 x2. I went to the nearest branch to inquire and they informed me that i have to phone 135 and report the issue. I contacted them today, which was within the 7day mark and i was informed that i have to pay 1month subscription + cancellation fee+vat which i dont understand. I obviously told them that i'm not happy with this an was informed that it will be escalated to the manager who will phone back.