We have been behind for the past 3 months. At this juncture, we owe for November's rent of $750. And yet our balance is stated as $1500!!

Yes. Late fees can still be assessed until you are current with your monthly rental amounts. Why wouldn't late fees accrue? You're still behind regardless if partial rent has been paid or not. "Creative" accounting is not going to work here. Sorry. Be thankful that your landlord has not filed an eviction proceeding for nonpayment of rent.