Doctor's office visit back in April. Pay co-pay. Get billed later and pay the difference we still owe. 4 months later get a bill from a company we've never heard of before that the insurance company uses with the words "insurance adjustment" on it. Call company and tell them we already paid the co-pay and the bill from this specific visit and I've documentation to show that.

Ask them what "insurance adjustment" means and they wouldn't give me a straight answer. Get transferred to 3 different people because they can't answer my question. Finally get a "supervisor" who tells me the adjustment means they went back and decided to retroactively apply the other difference to the deductible. I didn't even know there was "an other difference." So even though we paid the co-pay AND the cost of the visit, they decided to retroactively make an adjustment so that we pay more.

Such a scam. And of course if you don't pay the supposed difference (that we actually already paid) it goes to collections.