Donna claire riverside stinking attitude

I bought a bra on the 22nd of December 2018 at the Donna claire shop in Riverside, the item was not where the other items were aa they were at the back and that's where I saw it. I asked the lady to give me 42E and I also bought a jumpsuit with the same purchase. The lady had dreadlocks and now she is refusing to give me back the correct size coz according to her I wore it the whole day. The whole shop assistants were now attacking me because according to them I was giving them attitude and they went on to say how would I feel if they came to where I work and complained? I want the correct bra size that's all I want, they stinking attitude should not be my problem. That's not how you try to resolve an issue just coz I work in the same mall as them.