Landlord withheld $500 "pet fee" from my security deposit!!

[Account Closed]

I live in Nashville, Tennessee. 

I moved out of my rental house in September and just received a letter from my landlord that outlines the charges withheld from my $800 security deposit. I only received $250, with the main portion being taken from an arbitrary pet fee that I never agreed to!  

There was a line in the Lease about "no pets", but I didn't sign anything that agreed to paying a pet fee. 

Upon moving out I spent a considerable amount of time cleaning the house and making sure it was in excellent condition (The landlord is a persnickety old woman who is VERY particular so I was trying to mitigate any losses in advance). 

Do I have any leverage in getting my $500 back or am I just out of luck? 

The letter states the following:

• You did not change the central HVAC filter for 2 years that you rented my property. This unit was brand new when you moved in and I am concerned about the long-term damage. 
• Bath Room - removal of curtain and shower rod when you moved $50  
• Although the property was no pets, you allowed your friend to bring her two dogs when she stayed with you on the weekends.  After I sent you a letter on the issue, you continued to allow the dogs but tried to hide them from me.  For this reason, I am charging you a $250 pet fee for each of the dogs. $500
• Total $550.00

Enclosed you will find the remainder of your security deposit in the amount of $250.00     

Any guidance would be greatly appreciated. 

Thanks, 

Adam