How would i write this on my resume'?

I worked for the hospital for 3 years in dietary, until another food service company took over the hospital dietary. I kept my same position for 2 1/2 years under this new management. Then they demoted me from supervisor to office clerk... because they brought in their own supervisor. How do I write that on my resume' it's so confusing. Do I slash the companies because I was still a supervisor under the new management, and then they demoted to a office clerk in the same year I was a supervisor? How do I write that on my resume'?