Bad bad experience

I received a contract iPhone 6s from Vodacom on the 20th March. The speaker is very very low and battery doesn’t last, called vodacom on Tuesday 24th March and told me to voda shop. Went there and I didn’t get any help. Called again 25th no answer , called again 27th no answer , called 28th and they told me that I can’t get a new phone because it’s iPhone. No one explained that to me and what I heard is that with 14days I can call and get another phone. I am not happy at all and really don’t understand why you don’t explain everything to your customers....