Bad all around. First, An increase in electric due to it being cold is normal and comparing the coldest week of the year to previous months is not accurate. Second, You asked your landlord to make a change and they did it on Christmas Eve. They've also regularly been fixing things. That's a pretty good landlord. Burning them over $10 is likely to teach them to respond with "The condition of the windows is the same upon move in and while it may take slightly higher utilities That's why the unit is priced slightly lower".

Overall while it may be annoying that you had to deal with that, it's probably best to chock some things up to people being human. That type of flexibility will likely net better results than repaying Christmas Eve work by asking for money back.

If bills are tight due to utilities you might also qualify for DC's utility assistance program.