I have had a few through the years that did that, a good cleaning and servicing usually made the reserve a lot longer.
The rotor issue, once taken care of, should help immensely as well.
I have one 7750 that is 4 yrs old, and keeps great time, and has a reserve of about 33 hrs.
That is crazy! I certainly hope he learned his lesson. I think he should have been fired, but I am glad you received some sort of compensation for this.