Why do I have to refund a $80.04 check back to BCBSIL that I never received yet?

My two claims have not been paid and BCBSI just found the error and said because my doctor opted out of Medicare I had to pay the $80.04 that I have not received yet.  First, they lost the info for the claim; said I had the Naperville box #; (why didn't they send it to Chgo.) then, I submitted again and they lost the second part of the claim; thus, I faxed it and after I called, they told me they received it.  It took a long time to adjudicate.  They said the 20% they usually pay is going towards my out-of-pocket.  I don't think I should have to refund their error that I haven't even received yet. I have been an employee with BCBSI for forty-two plus years and am a retiree now.  All of this has been going on since January.  The computer even said that I did not have Medicare Part B coverage.  My husband and I have had Part B since April 1, 2009.  They also suggested that I change doctors because of the 'opt out'.  I don't want to have to start over with another doctor since I have many issues.  I had my last doctor in IL for 25 yrs.; I have had this doctor for the past five years.  The rep said I have to go thru this every time I send a claim in for this particular doctor.  This is a lot of stress for me; why can't it be simple.

Thx for listening.