Elmhurst Memorial Hospital, Greedy Billing Sent collection agency after me for bill I already paid Elmhurst Illinois

This actually happened in the '90's, but I figured I'd tell the story to see if anyone else had this happen to them here, or at any other hospital.
Back in March of '91 I was hit by a car while riding my bike, and I landed hard on my right knee. I had the driver's information, and medical bills were incurred. Emergency room, emergency room physician, radiology etc...... totaling about $1200, $1400 if you include follow-up visits to an orthopedic specialist.
Since I wasn't horribly crippled or anything, I settled with the insurance company for my medical expenses + $500.

They were aggressive in pursuing what was owed to them, like any service provider, and while I was waiting for the settlement to come, the bills piled up on my table, since they were coming in every month, I was throwing them away, mostly, knowing that I would be billed again.
When the settlement came, I started paying them as they came, $200 here, $300 there, and when a redundant bill would arrive, I would throw it away, thinking "I already paid this", and sure enough, I would never see it again.
Then, one day, I received a slew of bills in the mail, and I sorted through them and found a couple that I hadn't paid, so I paid them, then I found one that I thought I forgot to pay, but then I took a double-take, the amount looked familiar. It was a radiology bill for $38.

I checked through my stack of saved bills and found that there was only one bill for that amount, the radiology bill. Then I checked my ledger, I'd already paid it, so it went into the shitcan.

Well into the spring of '92, this $38 radiology bill haunted my mailbox bi-weekly. I tried writing them letters to no avail. I once tried to contact them to straighten them out. I was put on hold. After 15 minutes I put it on speakerphone and walked my rent check up to the office, I'm still on hold. I go and take a shower, I'm still on hold. I walk across the street to get some beer, I'm still on hold. Every 5 minutes or so, hearing a recorded message of how important my call was to them, and to continue holding. After 90 minutes on hold the recording said "I'm sorry, our business hours are....." I just decided "Screw them".

They kicked it to a collection agency. I called the agency and explained that I'd been trying to tell them I've already paid them, personal check #276, written on 11/18/91, received (according to the stamp) on 11/20/91, and presented to my bank for payment on 11/22/91. (Yes, I still remember the dates to this day).

The next day I got a call from the collection agency saying that they insisted that I still owed them the money. They accepted my offer to send them a notarized copy of the canceled check. $2.50 plus postage at my own expense.

A few days later, I came home from work and there was a message from the collection agency on my voicemail, that they were satisfied that I'd paid the bill, and that I wouldn't be hearing from them again in this matter. But for the next two years that I lived at that address, I still received "Final Notice" threats on that same bill. For all I know, they are still going there, seeing as I moved without leaving a forwarding address.

Wj
Palatine, Illinois
U.S.A.