First I would write a letter with facts to insurance coverage at time of service, how long she was in the hospital as well as her son.
She can also state that she never received any statements / correspondence, etc regarding their stay.
Ask for the hospital for an audit of the account, dates of when they sent statements and to what address...was it addressed to her or to the son.
Send a copy of this letter to the Hospital Administrator, Collection Agency and to Medicaid. Send certified. You will also need to include your Medicaid number that can identify you and / or your son for date of service in question.
This will be your official dispute. While this is being reviewed ... collection effects should be placed on hold.
She is told that it is "too late"...that is NOT true. They do not want to go back and try to figure out what went wrong. It could have been billed under the wrong ID or something else. It happens.
Approximately 10 days after you submit your dispute...give each one of them a call to check the status of this. Keep documentation as to whom you spoke with, date, time, etc...
Those three agencies need to communicate with each other to get it resolved and notify you all of the findings.
If Medicaid tells her that the hospital billed it incorrectly...whether it was under the wrong ID, name, etc... she may want to mention to Medicaid to contact the hospital directly as the hospital refuses to fix.
However a certified letter detailing all of this is the route.
Collection agency said they couldn't fix? They can't...generally if a claim was billed incorrectly...it goes back to the provider to fix and since the hospital said it is too old...yep, she is getting the runaround.
Zig