Are you being fired for excessive Tardiness (reporting late for work), or Absenteeism (not reporting for work at all) or both?
Is your Center Manager blissfully unaware of the "Innocent Until Proven Guilty" clause in the National Master???
Article 7 --- Local and Area Grievance Machinery
Except in cases involving cardinal infractions under the applicable Supplement, Rider or Addendum, an employee to be discharged or suspended shall be allowed to remain on the job, without loss of pay unless and until the discharge or suspension is sustained under the grievance procedure. Notwithstanding the foregoing, any superior provisions in Supplements, Riders or Addenda shall prevail. . . .
Sounds like you should be on a "working termination."
FMLA leave is The Law. UPS must grant you the leave if you qualify; they can't legally retaliate against you for invoking it.
You need to notify UPS in advance if you know in advance, but if the Flu sneaks up on you, you only have to notify them as soon as practical.
Even if you have never heard of FMLA or didn't intend on invoking it, UPS has the legal obligation to invoke it for you once you mention to them the medical reason you are not coming to work.
http://www.dol.gov/whd/fmla/index.htm
FMLA is described in Article 16, Section 6 of the National Master.
Just a thought: Are you being terminated just shy of reaching five years of Vesting, which is the minimum required to qualify for a pension???