Shadow Emergency Physicians / LabDraw.com review: sent me to collections when they didn't file the claim

I had medical coverage at the time of the service. The collection agency sends me a letter 4 YEARS after it happened and I called them and I was told to send proof of coverage for that date. So, I called my insurance company and they cannot provide me with verification- but said that I should have my medical card to show proof. IT was 4 years ago- I don't have the card. And my insurance company told me that there was claims filed for that day- but not by that provider... So, why send me to collections 4 years after the fact when they failed to follow through to file with my insurance company!