Promotion-Step Up.No one can help after 6 calls

I accepted a promotion,STEP UP offer 3 months ago to upgrade to compact plus & after 2nd payment get upgraded to premium for a month. I have SMS confirming this. I have called DSTV 6 times & no one knows anything about it. Sending mr from pillar to post. Escalated twice with no response. ***9/C1 & C2. I offered to send call centre agents the screenshot of the sms, they not interested & just want to escalate. I was bamboozled into taking a higher package. Understand now why people closing their DSTV & moving to Netflix.