Over charging and unreasonable split of bill

I'm renting a garden cottage,3 units on property. Advert stated pre-paid electricity. The meters are only there to indicate how much units we use. They split the Ekurhuleni bill into the units each house/cottage uses. I use 200 units/month,the property uses more that ****W which is a higher rate/kW bracket and they charge me according to that. They split the rest of the bill into 3 60:20:20. There are 4 people living in the house,4 in the Bachelor flat,I live in the other cottage alone. My water bill for Dec.'15 more than doubled,I was only there for a week and a half. The people in the house bought a portable swimming pool (457cmx91cm, water cap. 12 423 l) in Dec.'15. My water more than doubled again from Dec.'15 for Jan.'16. Brought this under the agency's attention in Nov.'15,asked them to reconsider the ratio the bill is divided. I can't pay the same as 4 living in the other cottage,they refused. After receiving my bill of ?R380 (between R55 - R75 the first few months)for Jan.'16,I asked them again to reconsider,they refused again and said\RAK will assess the next statement and implement changes if required". Since Nov.'15 to Feb.'16"