the collector is now threatening to sue me even though l have explanation of benefits paid 5 months ago to the doctor by my insurance.

The insurance paid their part, not yours. Even though you received an explanation of benefits, you may still be responsible for part of the bill.

On your statement it should state how much you MAY be liable for. In this case, you probably owe them money.

If the EOB states that u owe nothing, contact the doctor is office & make sure they did indeed receive the payment & make the necessary contractual adjustments to result in full payment. Then make sure they contact the agency & cancel the collection proceedings. Document ur conversation with the doctor is office in a letter to the collection agency & include a copy of the EOB. Request that the agency send u a written statement that the account has been settled.That should take care of the problem.

It is possible that the payment was received after it was assigned & the provider did not send that info to the agency.

This is exactly why EOB is should be filed along with bills to make sure that all is handled timely.