You have a right to heat, 68° during the day and 65° overnight from October 1 to May 1. It sounds like you reported the problem when you could no longer maintain those temps in the unit and like the landlord fixed it reasonably quickly in spite of the holiday weekend.

Typically, the only time you can deduct from your rent is if you yourself must make the repair because the landlord has not responded within a reasonable amount of time or if the repair is necessary immediately to ensure the safety and habitability of your residence.

While I don’t doubt your bill was higher this month, the outdoor temperatures alone can cause that even when a building is in good repair. There’s no way to prove what portion was due to poor weatherproofing.