def METHOD_NAME(self, username, course_key, new_deadline):
    """ Update Credit Eligibility new_deadline for a specific user """
    try:
        eligibility_record = CreditEligibility.objects.get(username=username, course__course_key=course_key)
        eligibility_record.deadline = new_deadline
        eligibility_record.save()
    except CreditEligibility.DoesNotExist:
        logger.exception('User is not credit eligible')
        raise