Faulty Samsung S5!!!!!!

I am disappointed! I am a loyal Samsung and Cell C consumer! My S5 was bought on a Friday and like the sales consultants explained to me I had a 7 day return period! As per my understanding of the explanation I had a week! (7 days) So on Friday morning I was told I can't because the time is over! I am fustrated by the fact that I was given a faulty phone and I am paying for a phone that was given to me broken! The battery and speaker are faulty! How can I be expected to book a phone in that was given to me broken? Are Cell C really about customer service or just want my money? Samsung I am disappointed in the fact that it is my Second Samsung phone with issues.My previous S3 Also had issues! How can I be a loyal customer if both my service provider and Samsung lead me to bad experiences..What makes me even more irritated is that I was going to switch over to Apple! However being brand loyal I stayed! I require assistance and a new phone! I can't wait 21 days or you can have the phone back because I can't struggle like this