I have been a non washer for a long time. However, I started a applique quilt with pink, dark pink, and green batiks. In the course of working on the blocks, I think I got a place dirty and rinsed the block. The red bled. I have hand washed the red now.
One thing I learned is that red has very large dye molecules. I use auburn hair dye, and hair dressers tell me it doesn't last as long because of this large molecule issue.
I have only had issues with red running, but purple is part red. Thank you for the warning. I think Prisim 99 is right in that what washed out is unset dye. However, it never should have made it to market with that much discharge. (enought to change a dark purple, to a lavender)
I do think I would take it back to who ever you bought it from and show them what happened. They may make restitution.