Terrible Customer Service

I went for my contract upgrade on Saturday 8 June 2019 at MTN Cresta Mall. I was assisted by Chansa. The cell phone was OK when i looked from the store. I got home i switched it On, within a couple of minutes i realized that the device is not user friendly in a specific manner. I went to back to the store on Sunday 08 June to see if i could exchange the device for a better one. I asked the floor lady if i can exchange the device, she wasn't too sure then she went to speak to another lady at the counter( THULI). The first thing i could hear Thuli say as she walks from the counter to another gentleman (Xolani) she said" AKUKONA EMADIZIN LA- meaning this is not a gambling place''. The first lady i had spoken just laughed. Thuli stood next to Xolani and started chatting to him whilst i was trying to explain my reason for the visit at the store. she was some 4 meters away from the waiting area where I sat with my son and other clients. I tried to get her attention and directed my query to her if it was possible for me return the device and take a better one, she went on being the rudest person ever. She was loud every person in the branch could here the conversation. She told me that I signed a contract and accepted the device I only have 7 days to return it only if, it has a technical fault. Xolani came in and said'' if they exchange the device that would mean i can take all the phones and return them. Thuli added on saying, i cannot just take a phone and decide over night that i dont like it and bring it back. " AKUKONA EMAKULENI LA'' meaning it is not some KULI's ****A SHOP. I asked what are the terms of terminating my contract, she told me to dial *135# and follow the instructions. I became extremely angry and told her to drop the attitude. I was then referred to Pascal an assistance store manager who positively explained the reason as to why they cannot exchange the phone. Pascal told me I was more than welcome to speak to the store manager on Monday. I contacted the store on Monday to speak to Chansa whom i had signed the contract with. Chansa called me on Tuesday to say they cannot exchange the device . It is just SAD that i will be paying for something that i wont use for the next 24 Months. i have been with MTN since 2008. i have two accounts .