Phone won't charge or switch on

Good day

On the 11th Of December 2017 I purchased a phone from Pep Cell. Two weeks back the phone switched off and it won't charge. I went to the store that I purchased the phone with the box and everything that came with the phone but they refused to assist me. I was told to bring the slip with me, I explained to the lady that I misplaced it and that can't they check on their archives which will reflect the purchased phone.

I am not happy about this. Phone is not even a month old and they refuse to assist me.