Thermostat is all the way up but apartment is still freezing. Help?

It's all fixed now thank you everyone! The temperatures for the next week are a lot higher thankfully so we'll be a lot warmer!

It feels like 7 degrees here and the past few days it's gone down to feeling like -16. I've had the thermostat as high as it'll go but it's freezing in here. The night it was -16 we were all warmer than we are now and it's 23 degrees warmer than it was. I can't do anything to the insulation but could something be wrong with the heaters?