denied severance

I was terminated because of a reduction in work force from a large company (company "a"). They have a written severance policy. I accepted a job with a different company that purchased one of the companies owned by the company "a". I was not offered severance from company "a" because I accepted the new position. The position was "not comparable" as defined by the written severance policy. I had 32 years seniority with company "a". The severance would amount to one years pay if paid according to their policy. I have written a letter to the severance plan administrator and was denied because I "did not receive a written termination notice and because I accepted employment with a successor company". I think because the position was "not comparable" as defined by their severance policy I should receive severance. I have the severance plan policy and can provide other documentation. Is this worth pursuing any further?