Is it permissible to cite certain excuses for not doing something requested by the father, without committing an act of disobedience, if the father does not treat his children justly?

Obeying and honoring one's parents is an independent duty for the child. It is not permissible for the child to neglect the rights of their parent, even if the parent has neglected the rights of their child. The questioner must honor their father, for honoring him is one of the gates to Paradise. And the father must fear Allah and be just among his children, acting upon the words of the Prophet, peace and blessings be upon him: "Fear Allah and be just among your children."