If you have to count on being able to refinance a 6% jumbo mortgage to make your payments, then you have bigger issues. The largest issue is owning a home you cannot afford.
As you may have found out, a low credit score is not going to have banks running after your business. A low credit score will hurt your chances to refinance to a lower rate and/or purchase the home of your dreams.
You should review your credit reports and make sure the information is accurate and dispute any inaccurate information.
Getting current and staying current on your credit accounts is the best way to improve your credit score. Negative information stays on your credit report for seven years, but you won’t have to wait that long to see an improvement in your credit score.
If you need help raising your credit score and removing harmful information, here is more information.