Santander Consumer USA Ripped me off with a high interest rate and took extra payments that were never applied. Nationwide

There is some confusion here with your understanding of how credit works.  If you are making each and every payment on time and Santander is reporting your timely payments, then they are not ruining your credit. I am not affliated with Santander in any way at all. Your post is confusing because you state that Santander is ruining your credit even though you  have paid more than the monthly minimum payment required.  The best thing for you to do at this point is to get your records together to show that you have made each payment on time and check it against the records that Santander has for your account. If there is a difference in what they are reporting, have Santander correct your credit reports to reflect your actual payment history. Then when it is correct, refinance with another lender at a lower interest rate. If you need to get additional information check the FICO credit report websites so you can see what steps to take next. At no time will making all of your payments on time hurt your credit. It only hurts if you don't make your payments on time.