Escalated Bill

Terrible service. Since we have moved in our bill has doubled and there is nothing new plugged in or being used and the geyser is on for 30 minutes each day only and still our bill increases each month? There is only two of us on the property and we are at work/university most of the day and our bill is now R1200.00 and started at R344.00? When calling we are told that it is due to being colder now.