Nancy, I wanted to post again and I will be honest in saying I did not read every response in this thread. I think I can give you a pretty analytical, unbiased take on the situation here. If your PM was scamming you, she would not intentionally fail to collect the late fee each month. I am a property manager in Upstate NY and we keep the late fee for reasons listed above.
There is no reason for the PM to keep the deposit in trade for the late fee. If the PM kept the security deposit to cover the cost of un-collected late fees, that doesn't sound like a scam necessarily, it sounds like a bad PM was trying to ensure they were paid their balance. Taking the security deposit in exchange, if that is what happened is not the way to collect.
As for the pet fee, you need to be clear on the expectations between you and your PM. What were the pet fees for? Was your management company doing additional work to ensure there was minimal pet damage to the property? IE special landscaping care to prevent dead grass, forcing the tenant to obey leash laws, requiring copies of shots, and licensing of dogs, forcing tenant to have additional insurance for the dogs that protect you? I can tell you now that your typical policy does not cover you if a dog attacks someone. For the PM to keep the $25 fee is very reasonable.
You had a tenant that paid late every single month by your own admission for at least 6 months and you're now expecting them to tell you the truth? I know late payments aren't indicative of a fibber but your tenant has every incentive to lie to you about the PM to paint themselves in a better light.
It is hard to think clearly when you're thinking emotionally. Carefully read your contract, if anything I think this is more of a case of a disorganized manager, not one that is intentionally trying to scam anyone. Never attribute to malice that which is adequately explained by stupidity.
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PS: Same deal with the security deposit. Do you know that is why they kept the security deposit? How do you know? If your tenant damaged your property more than what is covered by the deposit, your PM isn't responsible for that. You can sue the tenant for damages.