Mr Price Horrible service

I bought a phone at Mr Price Soshanguve Crossing on the 15th of june 2018,it was on display and it was gold.The lady brought the phone and did the settings on it and put it back on the box.When i got outside to my surprise the phone was black.I got back inside the store and they refused to exchange it.I have since left the phone at the store.I tried calling their head office and customer care but no one has been able to help me.An Area manager by the name of Mallen Gorvendor told me to stop calling him,im annoying him.Please help