You could try this form, although from the phrasing of the error message I would have expected to find more explicit contact information. The other threads mention this same feedback form.
I do happen to have the email address of someone at Mathworks who is involved with the FEX, but I don't think it would be polite to share their email here without their consent.
I would suggest trying this form. Remember that staff members might be in a different time zone. I would suggest allowing 48 hours for a response (not counting the weekend) before trying another route.
