No Help after signed contract

I find that the Cell C in Westgate Mall - Mitchells Plain is no good to their customers after you have signed the 2 years contract with them. I purchased a new Samsung S6 not longer then a month ago and its started giving problems where I cant use the phone. I went into Cell C Westgate Mall and ask for their Samsung Reps number because I need to get this problem sorted asap as I use it as my work phone. The manager in the store told me they do not have the number of their Rep and that I should take it up with Samsung. I would think they make more of an effort after I explained to them I need this phone for work, let alone the fact that I'm still their customer for the next 2 years.