First Premier Bank Posted a late payment on credit report even when account was paid in full nationwide

I used to have First premier credit card for over 10 years, when I asked them to wave the $7 monthly charge they refused to do so, I then asked for the account to be closed and I had the balance paid in full as it appeared on my online statement.

After a few monthes I received a notice stating that I owed them $9 on my account, I paid the amount in full then, enen though I had never received a notice of any kind before that, they still posted a negative late payment on my credit report which brought down my credit score over 50 points therefor I wasn't able to buy house because of that, I don't think that was fair at all.

I am still fighting this with the credit reporting agencies, but it's not easy dealing with them either.