Harrasment and ridiculous interest

Consumer portfolio services is the company we got our auto loan through. I have medical issues and have been out of work so we got behind a little. I made a payment this morning and got a phone call asking for money. The woman was rude and threatened repossession. They call 3 to 4 times a day every day and threaten repossession. I exploded on this woman this morning. We just made a payment and are catching back up, but they still threaten. I told her if all they are gowing to do is Harras that they could come and get the car. I have read complaints about this comany from so many peoplevels. The car we purchased was financed at 9000, we have been making payments and I asked what the payoff is and it's at well over 12000. I asked how that could be and I was told they accrue interest daily. How is this legal?