Have any of my rights been violated and do I have any cause to garner additional severence?

I have been Director of Purchasing for a small $15M garment manufacturer for 6.5 years. I have not had a review in 4 years. I was verbally complimented highly for my performance last Dec. and given a $1500 bonus check by the owner. The new COO of 6 months terminated me yesterday stating this was not an issue of my performance or personal, but he was reorganizing the purchasing dept.(previously me and 2 employees) and my position was eliminated. Someone else has already been hired. I am a 55 year old female. I was never told a reorg. was considered and never asked to be part of reorganization. I was never told the performance of purchasing was in question. I feel certain another individual from a competitor will replace me, doing exactly my job, but with a different title. The motive is likely to have access to the competitors factories and sources. I was given 4 weeks severence and promised another week if I accept phone calls should they have questions. I signed nothing and got nothing in writing. Have any of my rights been violated? Can I do anything to assure they will pay me the serverence promised? Can I do anything to negotiate for more severence pay?