Bad treatment by retail employees

My husband bought cloths for the kid on arrival I realized that the cloths are small I took my time took few hours from work to go and exchange the cloths on arrival I find only one pair that can fit my daughter I picked them and go to the till, on arrival I found a cashier she told me I can not exchange the cloths because the account used is not mine that their comp policy. I told them that I don't want to change the cloths I just want to to change the size they refused. I told but I have the receipt of the person who bought they refused and say they can't help me is against their company policy I have staked with small cloth that I can not use and I can not change because the person who bought them is out of the province. I am really disappointed thanks to truworths Kempton Park festival mall