ModCloth.com Customer Service Issues

Regarding order [redacted]54 for the red Chelsea Crew shoes in size 39, I've received numerous compliments on their adorable design. However, after wearing them only a few times, I've noticed a small rectangular plate under the heel cushions that is causing discomfort by pushing into the soles of my heels, particularly on the right foot. This issue is preventing me from wearing them further due to the pain it causes. I believe I paid full price for them, and I've worn them only twice for a total of around six hours. Shoe repair in my area is costly. Please advise on how to proceed with this manufacturing defect. Thank you.