They should have told you they were making a substitution. I once bought a kit and when it came the fabric was not the same as the picture. I still haven't made it up because the main fabric is ugly to me. I should have returned it but the extra shipping was too much for me at the time. Still irritates me.
I would mention to the LQS manager about your feelings and show her that it is not working. Give her the chance to give you a different fabric if you are not too far along, or a discount for future, or something!
Although, once you have it made and quilted, it may look a lot better than you think it is going to. The quilting makes a world of difference in tying things together.