i've attached my little mantra about dr. collections (sorry that it's a zip, had to get below 128K). pay special attention to points # 1, 6 & 8.
i love my doctor but his office staff is incompetent. I've had 3 items "go to collections" because they never billed my insurance. Contact your insurance carrier and have them contact the dr's office for you. The "assumed rejection" is the kicker. When this first happened to me, I had to call the insurance company 3 times before my drs. office finally got it that they weren't going to get paid. It was nice having an ins. co. fight for you - the claims helper actually sounded gleeful when she explained it to me (essentially the same info in the attachment
there is no downside to disputing it - in fact, it's the only way to get it off your report. you need to get this off your report if you want to play this game. You dispute it with the bureaus, you send a letter to the dr telling them to reverse all this carp with the collection agency and the credit bureau(s) because you are not contractually obligated to pay and they should know that and you ignore the collection agency (don't even answer the phone when they call).
If the facts are as you state, this is a slam dunk. It's just going to take a month or so to get it straightened out. And remember, when you get the letter from the dr.s office that it's been resolved, you pull all 3 of your credit reports to make sure...