I'm surprised that you are having a problem with them. I've never dealt with them directly, but my aunt ordered ink for her printer, a black a color and a special photo ink one because that's what the book said she would need. Turns out she didn't need the photo ink one and when she called Dell so she could return it, they told her they would refund her for the photo ink and she didn't have to mail it back. She got her refund no problem.
I hope everything gets figured out soon!