In order to answer your question, you need to carefully read your written lease agreement in that its terms and conditions control the obligation owed to you by the landlord and vice versa in the absence of conflicting state law.If the landlord's management company after a year and a half now sends you an invoice for utility charges in the thousands of dollars, the managment complex has a big problem on its hands. It is entirely unrealistic for you to pay a utility invoice well beyond amounts that you have been paying diligently over the past year and a half.I would write the managment complex a letter advising it of your position keeping a copy of it for future reference.Good luck.