Keeping money saved from companies budget allowance

I am an intern student in an organization, where we work on project basis, at last out of city project we were allocated a budget of Rs.6100 per day for our personnel expenses like meals, travelling and hotels. These expenses do not affect our work efficiency. These expenses were purly for our personnel expenses. Conditions was that if the budget exceeds 6100, the extra was to be paid from our own pockets. But in this project my senior made saving by selecting a very low standarad hotel. At the end of project he handed over half the savings to me.

I could not resist because if I resist they will hold back my actual expenses that were paid from my own pocket and also the whole organisation will go against me. Because to hold these saving is considered normal in my organisation.

Now the question is, is the money Halal or Haram for me?