Misleading adverti*****ts

I went to the Mtn store in Overport (the Atrium) to apply for the mtn 150gb month to month sim only contract deal. I was informed by the salesperson that I need to purchase the R1999 router to qualify for the month to month sim deal. However the magazine advert does not indicate the the router is a condition to the month to month contract, it says 'try the ...router. I does not say qualify for our the month to month contract when you buy the R1999 router. Furthermore, the advert says no strings, no obligations, no credit checks. The salesperson has made the R1999 router an obligation which is contrary to the advert. I was eager when I went to the shop with my documents but now I'm so disappointed.