Poor service from staff at Emondlo Mall

I bought clothes at pep in johanersburg I send them home at Emondlo with the slip hoping if the shoes won’t fit I can able to change them but when my sister went to pep Emondlo Mall she was not assisted they told her since they don’t have the same shoe they can’t help her , but she ask to take something else with the same price the didn’t want to help … please assist me with clarifying that if I bought something here in Johannesburg I won’t be able to change it if they don’t have the same product even if I want something else with the same amount