Damaged wedding dress

I bought a wedding dress at bridal wardrobe Lynnwood , Pretoria And the day of my wedding i saw rust stains on my dress very clearly and then when i took it back for cleaning i told them about it! They responded that they will talk to the managers and come back to me! So almost two months after my wedding they responded and only said sorry but i signed and agreed to any damages although they did not disclaim anything but knew about it! My dress was R24000 Now i cannot sell my dress and they only cover the cleaning of R950