cashier rudeness and insult

I went to pay for my daughters 2 shirts and 2 skirts ,the deal was buy one get the other half off .. On the computer screen it didn't look like the deal was coming up ,she didn't explain it properly so I just kept asking her and saying it didn't look right . She looked at myy dad who was standing beside me and said 'these kids nowadays thinking they can get everything for FREE' at NO point did I even insinuate that I wanted anything for free ! I was so insulted and will not return to zellers ! I will go to walmart now .