Understand how this works. Collection agencies get your file in one of two ways: they either "rent" the file from the creditor to collect on 33.33% contingency of anything they get; or they purchase the debt outright for pennies on the dollar and then collect for themselves.
They do not check individual files, they purchase them in what is known as "blocks" of a few hundred to thousands. This is a little inside information for you.
So once they this block, then they dole it out to their workers who call you and annoy/cajole/threaten you for payment.
The worker themselves does not know anything about the history of the debt, nor can you generally reason with them because they simply care about collection, period.
So trying to talk to them about how this is not really your debt generally fails - these aren't necessarily your smartest guys and gals here.
Now, nothing stops them from simply calling you and sending letters - they can do this - it is not illegal.
However, they are limited in how often and when they can do this. See your rights under the FDCPA:
We will get back to FDCPA in a moment. So, having said that, note that in Texas, the statute of limitations for debt is four years per Civ. Prac. & Rem. §16.004(a) (3). So they are way past that point. So they cannot really sue you.
This leaves them with a BARK, but no BITE - they cannot sue you, nor can they even threaten to sue you, because under the FDCPA, seeking unjustified amounts not possible by law ( 15 U.S.C. § 1692f(1)) and threatening arrest or legal action that is either not permitted or not actually contemplated (15 U.S.C. § 1692e) is not allowed, and is a $1,000 per occurrence violation!
So while they can try to collect, they are limited both in what they can say, and they cannot even file on you since the statute is out of limitations.
At this point, you may want to get their address, and write them a quick letter (to the manager, not the agent, and also to the president) stating all I have said and also adding that if they contact you again, you will contact an attorney to SUE them for FDCPA (they'll know what it is - believe me).
Now they have not done anything to warrant a suit yet, but just the threat of one scares any reasonable collection company.
Chances are, 95%, that upon receipt of that letter, they will back off, close your file, and decide you are not worth it.
I hope this helps.