Product: Vehicle loan or lease

I signed a loan agreement offered by Santander Consumer USA thru XXXX in XXXX of XXXX. Even though my interest rate was astronomically high at 22 %, they were one of the only lenders willing to work with me. My car was a little over {$15000.00} 2010 XXXX XXXX, for 72 months. I figured I could work that, even with a high interest rate, as long as I made every payment and paid extra, I could pay them off in no time! Fast forward almost 2 years, I had to request an extension that one of the reps suggested I get because I had moved to a different state for my boyfriends job. I did not find work as quick as I had hoped, and had already emptied my savings paying Santander 2 months worth. That was the 1st of a handful of extensions I had to get later on due to my dad passing and me having to take off work, myself sick and taking off, kids sick, etc. Santander has called almost everyday since trying to get more money out of me after I have continued to make timely payments-even reporting me late 16x on my credit! They replied the car in XXXX of XXXX and I had to pay almost 4 months worth to Santander to get it back-even though I was 3 months behind ( according to them ). About a week ago, they were harassing me, yet again, telling me that I was 120 days past due and needed to get current in order to avoid another repo. I asked the girl how that can be when I have double and triple paid them, AND Im on my 6th year-as we speak. This was the same thing I asked a rep nearly a year ago in XXXX around the same time. Both reps said the exact SAME THING! LATE FEES! Late fees?! How can I still owe late fees when I caught up twice with my payments and late fees and youre still telling me Im behind??? So how much do I still owe? I ask. {$10000.00} is what she tells me!!!! WHATTTT?!?! As soon as I got off the phone with her, I went to my job and spent all morning going thru transactions with them. I paid this company nearly {$25000.00}!!! And they were still telling me I owe {$10000.00} on a {$15000.00} car! I immediately called my mom and gave her my login on their website. I asked her to look over the numbers to make sure I wasnt crazy. She calls me back and had noticed something that I didnt .... they had applied ALL of the money that I had been giving them for my car towards the interest for almost 2 FULL YEARS. Then, towards the end of the 2nd year, they finally put 2 months of my payments toward my car. Right after, they went right back to putting the money towards interest- to the point where we are now ... that I have only paid {$5000.00} towards my car and {$20000.00}!!! towards interest!!!! This can not possibly be legal! Not only that- it was never made clear that when they were giving me these extensions that I would be accruing interest on that! I checked over the contract and I DEFINITELY did not get told by them or the dealer that ALL of my payments to them would go to interest for nearly 2 years! I am frustrated and very depressed from having to watch my credit suffer, as a result of these bloodsuckers constantly reporting me late and threatening to take my vehicle-after getting SO much money out of me for a car that is barely worth {$1500.00} XXXX!!!!! Please help!!!