Unclear terms on exchange of items

I bought a couple of items at Zara at the Cresta Mall last Sunday the 17.09.2017, one of which was a white T shirt. When I got home I was happy with the other items except for the white T shirt which didn’t fit properly at the arms. When I tried to return the T shirt for an exchange today the 22.09.2017 they told me that it had make up on it therefore they can’t take it back. I then challenged them to say nowhere in their exchange policy does say anything about them refusing to take things back because of make up that obviously got there as I was trying on the T shirt. They told me they can’t take the T shirt because they can’t re sell it. When I questioned them on what happens to the many items we find that already have make up on them, this lady who claimed to be the manager told me that those items found on the floor with make up on them are taken back to the manufacturer. I then suggested that they do the same with this T shirt coz I didn’t want it anymore. She didn’t want to hear me out instead she had the T shirt packed and given to me and wished me a beautiful day. I’m dissatisfied and disappointed because now I’m stuck with a T shirt that doesn’t fit me and the lady told me to go sell the T shirt myself to someone else since I don’t want it. She was rude and had attitude I’m thoroughly ****ed