I'd recommend that you put your attention on the volunteer work, and would be best if it's something that connects the dots to previous activities, so it doesn't look like a phony last-ditch attempt to Pander to the adcom.
I would let go of the whole feeder company thing. Then you would be in a position where you have to reestablish yourself in a matter of months.
Unless there's a serious problem with your supervisor, I would just ride it out and make sure that you lay the groundwork for a great recommendation.
With the volunteer stuff lay the foundation for a great recommendation from them to, that speaks to leadership, teamwork problem-solving and innovation. Because you're in more of a quantitative oriented role, I would like one or both letters to speak to your soft skills and mentorship effectiveness.
I've gotten tons of people in to Booth from No Name companies.
The first ten entries on my blog are geared towards someone like yourself who is preparing for round one.
Recommend you check them out.
you're sitting in a good position so congratulations. Look in the mirror and say go you, you.
Farrell Dyan Hehn, MBA
Admissions Consultant & Verbal Strategist MBAPrepCoach.com