You already know what happens: they claim they verified and validated and that’s it. Nothing you can do about.
So they want you to believe. But this is not the law. You have the right to see proof that indeed you owe the debt. Or that the negative entry on your credit report is really yours. If you believe them, you lose. Know the law and you will win.
This means you HAVE to demand validation. Maybe the first time they come back at you with “oh this has been verified and we are right and you are wrong”. Well, they are wrong. Because just saying they are right is NOT following the law. The law is actually pretty neat and it is on your side. But you need to know it.
The FDCPA tells you that you can demand validation. Once you have demanded validation, they must cease all collection activity until they validate. But your validation demand has to be in writing.
The wright validation is a wonderful tool to get your credit score back up where it belongs. By law!! And if they debt collectors don’t perform, then you have proof in writing! And you can use this to have them cited for violations of the FDCPA. Which means: not only has your credit score to go up. But you are also entitled for damages per the FDCPA violations.