Hello. My name is Marc. I'm a licensed attorney and I will be happy to assist you with this issue today.
Let's first make sure I understand your issue: Why did you receive 2 past due notices? Did you fail to pay the rent on time because your account showed that it was current (due to management's error)?
If management inadvertently credited your account, then they are entitled to reverse the error. Similarly, in a bank for example, if you deposit a check for $100, but the teller keys in $10,000, your bank account would show a deposit of $10,000. But, once the bank discovers its error (and they always do), your account would be adjusted to show the correct amount.
In your case, though, I'm not sure what the connection is between management's error and the past due notices. You should not incur any penalties, much less eviction, due to management's mistake. If your rent was late because of the mistake, they cannot penalize you. But if your rent was late for other reasons, then the past due notices would be appropriate.
I understand your apprehension about eviction. After all, those notices are quite menacing. I understand you attempted to clear up the matter with a letter to management, without much success. This matter may require a face to face discussion - or at least a phone call - in order to expediently clear this up. It may be much easier than you think.
Feel free to answer my questions above by providing additional info, in which case I will elaborate on my answer. Meanwhile, if the info I've provided helps you to better understand your issues and options, please be so kind as to rate my answer, since that is the only way I can receive credit.
I look forward to hearing back from you. Otherwise, I wish you good luck and a speedy resolution with management.