Yeas ago, I actually worked for a collection agency, in the computer department (so don't throw rocks). Sounds like you're disabled, which usually means a limited income. If you call and explain this to them, they will send you paperwork with your income vs expenses. Also assets. If you have no legitimate assets and not enough income and you are disabled, you will probably be considered uncollectable. In other words, you aren't worth suing because you wouldn't be a successful win in a court. So I think the main thing you have to worry about is the trade-line and score on your credit reports.

If they are outside collectors, they must all abide by the PL95-109 law. If they are collecting within the company you owe, then, I believe there are different rules governing them. If they are harassing you afterward, you can write a certified letter to them explaining you want no further contact with them until they are ready to take the next step (like lawsuit), they are not allowed to contact you. All outside agencies have to answer to the attorney general of that state. And believe me, none of them like that. So read the law and no your rights. Document and report violations.