Literally the same thing happened to me without me knowing a long time ago. It was from PayPal, and they sided with the other guy even though I wasn’t involved (it was some punk bitch named Richard Lucarelli.) I had moved states a few times for work, so I hadn’t gotten any of the debt collection mail. When I did actually realize I owed it, a few years had passed and they could no longer legally pursue it.
What I mean is that if there is any chance you do actually owe money and you’re not able to come up with it, I wouldn’t contact the collection agency because it then re-opens the window of time they can pursue your debt owed. I only found out because I talked to a lawyer when I realized the damage my credit had taken. I want to say it was three years, but it might have been six. I’m sure you can find it on Google.
If you DO actually end up owing money, I’d still wait a while to pay because these debt collection companies will sell your debt to “lesser” companies for pennies on the dollar and often they’re willing to take 50%+ off what you owe. Credit is relatively easy to bring up, but paying money I don’t owe is unforgivable.