I'm Lucy, and I'd be happy to answer your questions today. I'm sorry to hear that this happened.
The loan IS closed because it was paid off. Because it's accurate, that's unfortunately not something that you can have changed. There are multiple factors that go into credit score, including the age of open accounts, types of accounts, and total credit utilization. If the mortgage was the only installment loan you had on your credit report, paying it off unfortunately decreases your score. Adding a loan account would bring your score back up.
Another option is to increase the limits on your credit cards. Part of your total score is credit utilization, and a person who low credit card balances and high limits will have a better score than someone with low balances and low limits. But I'm afraid there's no cause of action against the credit bureaus for accurately reporting that you paid off a loan, even if that made your score drop.
Credit Karma has a tool that lets people play with different scenarios and see what will change their credit scores. That's a free service, so it might be worth looking into. This is a free service (no card required for sign up).
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