Bad service

I bought shoes December 16 for my daughter who's in Cape town, when she got back to JHB weekend of the 25th the shoes are small took them back at East Rand Mall was told I can't exchange them because 30 day's has passed.My question is that what happened to customer service and I believe it's my right as a consumer to exchange a small item which I didn't use still in good condition with the POP.