Advice for no action on debt collection.

Hi!

I need help advising my friend. This is the situation as I know it - they racked up about $20k of unsecured debts in 2021/22 from a failed business. Creditors and collections hounded them for years. There’s still one agency contacting them. They are under the impression that if they ignore the debt and don’t engage with anyone over it for two years it can’t be collected on. Is this true? And then it will all fall off their credit report seven years after it defaulted?