Faulty Product

I bought a dress and it was delivered 08/11/2017 order number ********** . I was so excited I wore the dress on Friday 10/11/2017. While I waswearing it I saw there was a fault with the pockets, one pocket was so small I couldn't even fit my whole hand in it. On Monday 13/11/2017 I advised Superbalist and I corresponded with Holly, she asked me to send the pictures and I did. She told me I can't get an exchnge because I wore the dress and the product isn't faulty, it's a "design Feature". How on earth is a dress designed with only one correct pocket and you claim its that way. She also said I can't get an exchange because the dress was worn, why must I be stuck with a faulty dress because you failed to do your quality checks? Im disgusted by your service. If I can't get an exchange then fix the dress. I refuse to be stuck with a faulty dress pbecause of your poor service! I demand my exchange!