Debt collection company refuses to send me a statement?

I believe it may be from a hospital ER visit. I called the hospital, and they stated they no longer have an account for me. I called several numbers beginning with the number recently posted on my credit report. I eventually reached a man and he is threatening law suits, etc. I gave him my correct address, and I requested a statement. He states they have sent out 3, yet I have absolutely nothing. idk what to do. HELP. I want it paid if I owe anything but I refuse to make a random payment over the phone.