SANTANDER CONSUMER USA CAR LOAN FROM HELL DALLAS Texas

 You didn't choose them to be your lender, you were placed with them because a bank, with much lower APR wouldn't do business with you.  Why?  Because prior to this deal, YOU destroyed YOUR credit by giving YOURSELF a reputation for not paying YOUR bills on time.  As such, you are NOT ENTITLED to a free loan or a low APR.  Of course, the smart thing to have done was read the contract before signing it and if the APR was too high, then you don't sign it. 

"When I tried to trade in my car, my car was appraised / worth only $5,000."

That is not the fault of the finance company.

"However the Santander takes advantage of overly charging consumers."

What is the overcharge? Are they charging you more than the amount you agreed to when you signed the agreement?

"Plus when you do pay your car loan they charge you additional $10.00 to process your payment."

Mail them a check. The address is: P.O. Box 660633, Dallas, TX 75266-0633.

 This happened at the end of January and you are now just going to see a doctor about your Jaw?  Even if your Jaw is cracked, you lost any leverage you had and will not be able to prove that the event at the end of January caused it.

But let's just say that you are actually able to prove that your jaw was damaged, you are going to have issues in many other areas.  First you were well enough to check-out, you didn't inform ANY employee while you were in the store, and you were able to call the manager from the car just a few minutes later.  Then that night when you went home all you did was take a couple of Alieve and didn't go to seek medical attention.