Legalities of MTN

I have been a client for more than 20 years. I make an effort to GO INTO a store to do my upgrades. Let me explain your first disgraceful tactic. I went into your very fancy morningside branch sandton like I usually do. I needed another phone. I decided on an OPPO because my daughter wasn’t with me, I went home. My daughter didn’t want the phone, We didn’t OPEN it , everything was as is. I was NOT allowed to make an exchange to an iPhone. I wasn’t asking to cancel the contract . I just wanted another phone and was willing to pay more, They say they do not exchange . Against company policy, Now I ask you , is that even LEGAL? You are behaving like *******. No exchange or returns in a matter of hours. Is this LEGAL?