It's fine to turn on the heating, but it won't do you much good if you have a draft blowing in through gaps in windows and doors. You can dramatically increase the energy efficiency of your home (and your comfort) by installing weather strips on doors and windows.
The cost of weather proofing is completely dependant on the house in question, so we will bill based on material used and time spent at the property. Top quality weather strip sells at about R25 per metre (a door will use about 5m and a window approximately 2.5m). Application time will be approximately 15 minutes per door or window. So to give you some rough ideas of full costs including call out, labour and materials:
1 door and 2 windows: Approx R490
2 doors and 4 windows: Approx R850
3 doors and 8 windows: Approx R1,190