If it is a apartment. You should call the super or landlord. It should be fixed by them. You should not do it yourself without permission.
If it is your house, it is called baseboard heater. You can get them at home depot or canadian tire. There is two kinds. One is 220v . One is 110v. the 110v usually is portable one. 220v is installed fixed. It has special 220v wire for power. You just buy one to replace it. It cost about 200-300 dollars. Simple job.
I don't think there is anyone fix electric heater. It just too cheap to be fixed. If you can't do it yourself, check yellow pages for handyman.
