Called them a month ago after receiving phone mess...

Called them a month ago after receiving phone messages. Radiologist billing me for preventative mammogram that Blue Cross already paid them for.
Our policy covers one preventative mammogram per
year. Called the radiology office and the employee told me they were paid by Blue Cross, months ago.
I am calling again tomorrow because it looks as if CSI is operating a billing scam. Today it showed up as a collection on my credit report. From the the reviews, this place should be shut down.