Naartjie (Truworths group) exchanges

I received a Naartjie dress as a gift for my toddler daughter but it was slightly too small. It was unworn with the tag. I went to a Naartjie store to exchange it for a bigger size (as I have done before) only to be told by the assistant that I must have a gift receipt in order to do this exchange, as this is the policy of the Truworths group. I received this gift from my great uncle who is 90 years old, how should he know he must retain the gift receipt as most retailers allow exchanges in this scenario. When he purchased the item, this policy was not clearly displayed or communicated to him by the sales assistant. This policy is not consumer friendly, especially for childrens clothing retailer.