Tek Collect Rude, not helpful, would not provide any information Columbus Ohio

I have been contaced by Tek Collect for a supposed medical collection for my son who is a minor. The first time they called - over a year ago - I advised them that my son was a minor and that my insurance (which I pay handsomely for) should have covered the charge. I was told to send in a letter disputing the charge - which I did. I also asked for a letter or statment identifying the charge and the dollar amoung.
Four months later I received another call from Tek Collection - asking to speak to my minor son. I again advised the collection rep that my son is a minor. I again asked for a letter or statment advisng / detailing the charge. I was again asked to send another letter disputing the charge. Apparently they never received the first one I sent - and the person I sent it to is no longer with the company.
I sent another letter. Still did not recieve a letter or statement from Tek Collect detailing the charges and the amount.
Seven months later I received another call - same thing - asking for my minor son. I went thru my explanation again and the folks I spoke to previousley and the woman on the phone for Tek Collect was so rude to me. She told me she never got the letters and if I didn't send them certified, then they would not be accepted. I asked if this was a new policy because the last to representatives I spoke to never mentioned I needed to send the letter certified. The woman would not let me speak she told me to shut up and just pay the bill. When I asked her if she could send me a statement or a letter she said no they don't do that, and I tried asking her how can I be sure that this is a valid charge if I don't have a letter or statment to verify with the client (medical agency) that I in fact owe this. Again the woman from Tek Collect told me to shut up and pay the bill. I asked her how much it was as she was about to hang up on me. Now I am thinking that a collector gets evaluated on how much they collect, so why she was in a hurry to get me off the phone without telling me how much I owed is beyond me. I did ask her for the phone number and she rattled it off and then hung up on me.
I called back directly and when the person (a man this time) answered the phone he just picked it up and said "hello" so now I am wondering what kind of scam this is where this company calls people telling them they have collection items, but won't give them any sort of letter or statement they they owe it. And then don't even answer the phone with the name of the company. Seems fishy if you ask me.
So it has been a month since I have asked again for a letter or statment detailing what the charge is and I still haven't received it. So that is my story, these collectors are rude and obnoxioius. I am a good citizen and pay my bills on time and I hate to think that some folks are falling for this and possibly paying for things out of intimidation.
Stay tuned for further updates! LOL

Md
Dearborn, Michigan
U.S.A.