Collections Problems

I am dealing with Edwin Parry law firm in UT currently, and have been trying to reason with them to no avail. They did get a judgement against me (they bought the debt from my doctor), and garnished my wages with my previous employer. I am no longer employed with that employer, so the garnishment stopped. I called Edwin Parry's office to arrange a payment of $300 bi-weekly (I owe around $1900, and they already garnished $600 before, the original judgement was for $2500). Not only they wouldn't let me make those payments, which would have been more than garnishment amounts they were taking bi-weekly from me while I was employed, but they demanded I pay in full, $2500 amount without considering the garnishments paid already. Demanded that I drove the check for the full amount to them right that afternoon (when I asked them for their address to overnight the check, they refused to give it to me. hmm, doesn't make much sense to me). I did look them up online, and they only list a P.O. Box, no physical address. Moreover, they told me I am a lying scum, no good for anything and a real thief. I was floored to say the least, as I called them voluntarily to arrange the payments. Before I hung up, they told me they will hunt me down, lien my bank account, and find and show up at my work to embarrass me if I don't disclose where I work that same second I was on the phone with them.

Anyhow, here is my life story, I am a little disturbed by the way they treated me. I also read some reviews on them, where they went to courts and obtained several judgements against one singular case, adding on their "attorney fees" each time. I am not sure that is legal, but I see they are not that much concerned with adhering to law or ethical practices, and really count that people like me wouldn't know what to do.

What would you suggest, hire an attorney or what could I possibly do? One of my friends suggested I just keep sending the payments to them, but I am afraid that 1. they will find out what my bank account is; 2. they will take the payments without noting them and again will enter the judgement against me for even more money (which seems to be the case for several of their debtors reviewing them online). They are not interested in working out a plan with me; and I don't want to call them any longer, they treat me like I am the worst of the worst. They just sent me a statement stating that they are planning to obtain an Order for Supplemental Proceedings against me. What does that mean, can they take my one and only super old car I own, which is paid off?

Unrelated note: can anybody recommend good debt-settlement companies in Utah?