gift bought from account exchange

My sister bought a pair of jeans for my daughter at Mr Price waterfront. She gave me the receipt for exchange purposes as she stays in Pretoria. Unfortunately the size was wrong so I went to Mr Price in Canal Walk just to do a size exchange. I got the right size at the same price . I stood in the queue for about 30minutes before I was able to be served.I handed the jeans as well as the receipt to the cashier. She didn't see any problem as the price was the same but told me she has to call the manager to explain the situation. The manager came with a very bad attitude didn't even want to listen .He told me my sister has to come herself to sign and do the exchange. How on earth can she come from Pretoria to Cape Town just to do a size change for an item bought on her account ??? I am soooo disappointed worse my daughter wanted to wear it tomorrow at her school's prom night . Is this how your company treats customers ??????