American Suzuki Financial Services

My account has been paid in full and closed since 2/13/14 and recently the company reported on my and my husbands credit that we are 30 days late and our account is derogatory. Our credit is now negative over 30 points because of this and I was told that it will take 30 days for this to be fixed. It should not take that long and this was there mistake that needs to be fixed.