Know Your Rights
You have legal rights. Some involving what you have to pay, how to settle, how to avoid threatening calls, wage garnishments, and so forth. If you simply let the agencies walk all over you, they are going to do so.
Rather, learn your rights. Yes, a lawyer can help tremendously on this front. But, for your own benefit, and to properly deal with the collection agencies agents who are calling you non-stop, it is also a good idea to arm yourself with legal knowledge. Doing this shows them you understand what is going on, and that you aren’t going to let them walk all over you.