Poor customer service from a stand in manager

I am still shocked at the customer service we received at Totalsports Cape gate. My husband returned a pair of puma slippers we bought on December 24th. The shoes were too small for the child we bought it for. The lady Ntombi assisting us insisted it's been worn and she can't exchange it. The more my husband told her it was not worn and only fitted on she continued to say so is your house that dirty since she can see there is dust on the shoe..Infront of other customers, it was so embarrassing and an insult to talk about how dirty my house is. That's unacceptable, and to top it all she's the stand in manager on duty. We are extremely traumatised and humiliated by this event a day after Christmas. Somebody else had to assist us and she, Ntombi didn't even feel the need to apologise for what she said.It left a bitter taste and I will not go back there again.