Sonora Quest Laboratories – Charged again from services I already paid for.

I paid $230.00 because I got an email saying I was past due. I have always paid my bills on time. I called 3 times to Sonora Quest and finally got through. I was told there was a conflict between UnitedHealth care and Sonora. I was told I would be getting refunds. I have gotten 2 or 3 but have yet to get one for the $230. I stay on hold for over a half hour and still no service rep answers.