Telkom Upgrade went wrong

I went to Telkom Paarl Mall on 26 April 2025 to upgrade my cellphone contract. I asked the lady who helped me what is the upgrade phone for the Samsung A73 I used and she told me the Samsung A56. So I upgraded. Back at home I compared the cell and was shocked when I realized that the cells are basically the same. So I went back to Telkom Paarl Mall to return the cellphone as I was not happy. It was still in the original packaging, but I was told I could not return it if there isn't anything wrong with the cellphone. This is not what I was told while upgrading, as I was just told to return the phone within 7 days if I am not happy with it. I tried to return it within 7 days because I was not happy and I was refused. I want to cancel the upgrade and the manager told me I must send her an email which I did. I am still waiting for a reply and answer. Please assist me with this. I am really upset and want to cancell the contract.