Unable to get refund for cellphone bought from pep cell midrand

I went to pep cell midrand at the boulders shopping centre to return the phone i bought as is very extremly slow and i was told i must come back when the sales agent is at work. The staff attitude very horrible and when i ask questions i was told i should ask the person that sold me the phone and she is the only 1 that can assist with refund. I had to go somewhere that afternoon and i send my friend to go on my behalf as adviced to come after 1 and when he got there he was told they will not refund. Why did they make as to come back if they knew they will not refund us and according to them the phone is written that the ram is 500mb which means that the phone is slow. Pep cell does not even diserve a star