Unhappy with Woolies Greenstone

I am a very unhappy customer, I’ve been nothing but a loyal customer to Woolies over the years but the way I got treated really made me wonder if they really value their customers. I bought my newborn baby stuff earlier before giving birth as expected to prepare for my delivery, however didn’t use all the clothes and yesterday decided to return the brand new clothes tht I bought at Greenstone mall to go swap them with other clothes at the same shop but was rudely told by MARY who’s apparently she’s the manager there that she will not take the stuff back with all the price tags and all as it’s not on the system anymore and she doesn’t know what I must do. Really disappointed as I find this pathetic I mean I don’t even want a refund but to exchange. U really don’t value your customers at all