Normal price for a special price

In February i saw an Add from DSTV that you can upgrade a pay R599 for Premium. On the ad they say you can use Self-services, which i logged in and did the upgrade. I then suspicious that this not the correct upgrade that i have done, it is a normal upgrade.

I then called into the Multichoice call center to rectify this. The lady i spoke to did not have an idea of the special i was talking about. She then place me on hold, and came back to say that she rectified the upgrade.

So, in my mind i have been upgraded to the R599 special. Somewhere around the 25th of February, i made payment of R600. I then got a sms that i have to pay R411 more because i did not pay enough. And a debit order of R353.59 went off. This Month i paid R980 for DSTV.

I would like to know why would they say there is a special for R599 but they charge us normal prices? They are playing us or is just me ?