My question involves an eviction in the state of: California
My landlord has served me with a 3-Day notice for the month of September. I had made a partial payment earlier this month of $900 against a $1200 total. When I received the 3 day notice today, I find that they have applied the $900 to outstanding late fees first, showing a much higher amount of rent due than the $300 balance. The notice shows a "rent due" amount of $466 instead of $300. And then there is a separate designation of "late fee" as $27.96. This would appear to be a "late fee" on the outstanding "rent" of $466 for August. But that would also mean that they are charging a "late fee" on an outstanding "late fee" since the actual rent outstanding is $300.
So aren't they basically calling the late fees "rent"?
Background: the building is rent stabilized under Los Angeles rent stabilization and they are currenty charging the maximum amount legally allowed. I have lived in the unit for 17 years. The original 1-year lease has a 6% late fee clause. The original management company designated in the lease no longer exists and the building is managed by a new company. I have been month-to- month for the last 16 years. When I have paid rent late in the past, I provide 2 checks: 1 marked rent, and one marked late fee. I was late July and August and have only paid the outstanding rent, not the late fees.
So, in summary, is it proper and legal to apply rent payments towards late fees first?
(Also, the 3-day notice was left on the floor outside of my front door. Does this constitute proper service of a 3-day notice?)

