Telkom doesn't care about their customers

Don't talk to brand sales consultants. I went into Telkom looking for a phone that fits my hand. The demo phone I was given seemed to be small enough. The then cloned my phone on the new phone, I collected and then went home. I then discovered that the cover made it too big for my hand and it felt it was a bit heavy to operate with one hand. Next morning I went back and then they refused to take the phone back. I feel like my consumer rights have been violated.