Disputing Debts: What if We Can't Reimburse Subrogation to Erisa Health Plan Administrator

My question involves collection proceedings in the State of: WA

Car accident personal injury settlement received directly from third party insurance company because an attorney withdrew from case.

This was an ERISA plan from my spouse who was an employee for that company...I was just an dependent on her insurance.
Now my spouse even not working for that health insurance company for last 4 months.

Before attorney he withdrew he voluntarily said to health insurance administrator company that my client owes to 2k which in fact is not true because
settlement received was just a nuisance value ...at fault driver's insurance company did not pay medical costs connected to accident. So in my opinion
I don't owe them anything.

Now they are asking for 2k ...what if I can't pay them?
We don't have that health insurance coverage any more so we don't care...

Can they sell the debt to collection agency or they have to sue us and get judgement first ?
What else they can do to get 2k they think we owe them?:confused

Disputing Debts: What if We Can't Reimburse Subrogation to Erisa Health Plan Administrator