A C S Recovery Services

I was in an accident 7-5-2008 in which I was air lifted to [redacted] Hospital. ACS is billing me for $2855.72 stating the reason is that my health insurance, [redacted] over paid a claim that was already paid by [redacted] Ins. I never received funds from [redacted] or [redacted] and all the documentation provided to ACS proves this. I have asked for a copy of a check showing I cashed said funds but I just continue to get a delinquency notice and an itemized bill from the above date of service as well as a date of service of 6-12-09 and 6-19-09. Both DOS's from 2009 have nothing to do with this claim and I called [redacted] and confirmed all I was due was a $20 copay which they show paid. We have attempted 3 way calls with [redacted] and ACS to no avail. I have dealt with many reps at this agency and most recently [redacted] @ ext [redacted] She has failed to resolve this issue and I need resolved immediately.
Account_Number: XXXXXXXX