What should I do next?

On February 10th, for work I was asked to take a drug test. After submitting the test, I was under the impression that it might fail the test for marijuana, so I alerted my supervisor. At the end of the week, they alerted me that I indeed failed the test for marijuana. They had me finish an entire work week, whereas others who failed their test were terminated that day, feb. 10. I asked them if I could resubmit the drug test, because I hadn't smoked in a couple weeks, and they said no. The HR manager then tells me of a page in the employee handbook that says that any employee can appeal their termination. You have five days from the incident. For those five days, I called the HR manager 3 or 4 straight days to no prevail. So I left her voicemails each day leaving her with a return number. She never returned any of my calls. They are not following their own written procedures and policies. After I was let go, the had a meeting at work to notify employees of their new drug policy.