Customer not happy

My mom jst got a bad experience now at woolies cavandish Square she was returning a dress that she bought in November there at Cavendish, but she did not wear it at all been in the wardrobe seens then. Now they don't want to take it they say it was worn and washed but the tag of the dress is nt wet nor damaged. She wanted to take school things for my brother bcoz her budget doesn't add up that's y? She is taking the dress back and she told them she doesn't want it and left it there. So can u please help her ASAP.