Misleading adverts instore

I visited the bluff shopping mall on Sunday 01st October, upon passing the cell c store i noticed a special advertised boldly for R199 for 20gb data and a router included per month, i went in to take the contract, the sales assistant who was attending to me stated that the system was showing the deal atR239 and she was not sure why, however she agreed to get back to my dad on Monday the following day, when she finally did she informed him that the special was over on that Sunday, firstly my argument is, the sales assistant was not aware of this and wasted our time filling in the documents etc, SECONDLY the adverts were still posted up all over the store misleading customers about this deal, this is definitely WRONG on cell c path, i want to know what they are gomna do about this because i am very disappointed