the amount of severance & termination is $6500

I was previously employeed in a sales division of a company, which is state and federally funded. That division was eliminated. I was given no formal termination, but was told that I should contact the company that had taken over that division. I repeatedly asked if there was another position available but did not recieve an answer. I contacted the company, and was hired.
Now the company that I worked for refuses to pay severance, and terminatin, as stated in the policy manual. Instead they are continually pressing for a letter of resignation. They contend that since I accepted another position that I was not terminated, but that I quit. Others who still have not found employment have recieved severance and termination benefits.