No return on brand new phone

I bought a brand new phone from vodacom, as i needed to send my in for repairs.

Unfortunately the store, didnt have the device i wanted, and i opted for the one they advised. To my regret the phone isnt up to spec and i dont like it, i went to return the phone a few hours later and was told i cannot return the phone because my sim card has been placed in it. How else would i have tested the phone, if i didnt put my sim card into it.

Where is the noted 7days exchange or refund?