Misleading a customer

On Friday 29 September when I took in my phone for repairs to MTN, I was referred to a guy 'from Sony'. This guy then tells me that my phone will be fixed under warranty. I book in my phone and after numerous calls and being sent from pillar to post, get told that my phone will not be phoned under warranty. When I asked why the Sony guy said it would be, I get told he doesn't work for Sony. When I eventually get hold of this guy's employer, I get told he doesn't have the authority to speak on repairs and warranty. He is simply a promoter. My question is, why did this man feel that he has the right to tell Me lies? This is utter nonsense.