Clairz shop at maponya mall are ******

on the 19/09/2018 my younger sister went to a shop called clairz at Maponya mall to purchase a bag upon her arrival she mistankely purchased a R400 bag and paid , my mother arrived at the shop while the transaction had just been done and notified the shop owner that my sister purchased the wrong bag its not what she wanted, and indicated to the owner the bag she wants which costs less than R100, the owner then refused to give her money back and said she must take a bag above R200 which does not make sense because my sister was still at the shop had not left the shop . they refused to fully refund us our money back and forced my mother to take a bag that costs 250 something that she does not even want. the consumer protecting act allows for exchanges to be done especially considering the time frame this is in a time frame of 30 minutes....we are unsatisfied and have been heavily exploited to top it off the staff was very rude, its evident this is how they trap customers. may we please be assistsed with this complaint its serious injustice