Not sure if it's the same company or not, but we did about 3-4k worth of work for them in 2003 and 2004 and finally stopped because we couldn't tell what they were paying for.
They would send random checks in random amounts with the invoices mailed ahead of time ("just letting you know what we're about to pay you for" -type deal), but the invoice info they sent NEVER matched up to anything we sent them.  There were never names or order/file numbers or anything to go on to try and figure out which orders they were paying for.  We never seemed to be being paid fully, but had a hard time balancing the books and getting someone on the phone and trying to explain this to them was impossible.  It finally got to be just too ridiculous and we stopped doing work for them.  Like I said, it was a while ago - we don't even have their address on file anymore, so I'm not sure it was the same company.  Good luck!