OK, friends the update:
They called me this morning, exactly ONE HOUR before I had to drink the second 10 oz...which was to be followed by the third 10 oz an hour and a half after....rescheduled me...for Tuesday. The machine was broken....so while I wasted drinking 10 oz last night, thankfully it was not after I had polished off ANOTHER 10 oz....
SO, same thing...different day. I have to go pick up another bottle to replace what I already drank, and repeat Monday night for Tuesday.