If they are paid collections...GW..I've had success with this also on paid medical collections. I have one I am still working on. I plan on sending them one a month until they break or it comes off my report.
If they are unpaid...PFD. I've had some success with this.there's been one I haven't. And I am not paying until they agree to delete. Or I am forced. Just be careful of your SOL.