Recently got terminated from a publicly traded company i worked for 7.5 years without a cause, i was never told the reason i was let go. (i’ve heard restructuring and eliminating my position was a reason but two days before my termination new job openin

Recently got terminated from a publicly traded company i worked for 7.5 years without a cause, i was never told the reason i was let go. (i’ve heard restructuring and eliminating my position was a reason but two days before my termination new job opening surfaced on job hunting websites for my department and position) someone even called me on my cell asked me if she could get interviewed for this job. (This is how i found out)
My employer (hr) emailed me a severance package with 6months (-15%)lump sum payment to be paid out on next payday. Next day i followed up with redlined doc. To correct my name, my title, asked to add mutual disparagement agreement, and asked if i could get a premium for cobra since they wanted me to help them until the end of the year if they had any questions. employer never responded to my emails or never sent me updated or corrected version of the doc. After weeks of follow up emails i demanded a phone call. Finally 4 weeks later head of HR called me and told me company was in a bad situation money wise and they can not give me my severance. He said I’m sorry and hung up on me. What are my Rights and chances And can i go after them to demand what they promised me?
Thanks,