You need to carefully read your written lease with your landlord for the unit rented in that its terms control the obligations owed to you by the landlord and vice versa in the absence of conflicting state law.Read the provision concerning payment of utilities and how this amount that you are obligated to pay is calculated on a monthly basis. This provision should answer the questions that you have asked.If the written lease is unclear as to how your utility payments are calculated, you need to call your landlord about such and ask for clarification. If your apartment compelx does not have individual meters for each unit and the meters are tied to common areas, it does not seem fair that you pay pro-rata for such on a monthly basis for this unless the written lease specifically states so.You need to follow up with your call to the landlord with a written letter confirming what as said in the conversation.I suggest that you contact your local landlord tenant clinic or "legal aid" program in your county over this situation.Good luck.