Booked On Two Different Planes

We are americans in Sofia with tickets to Paris for tomorrow.  When trying to check in this morning we found that we are on two different flights.  Our Ref # are 2XSFNL and ZBLTVJ.  These tickets were booked on the same day for the supposedly for the same flight and paid for by the same credit card with one payment.  We cannot call the local Air France office because it is a national holiday here today, and we have been unable to connect with the desk at eh airport, it rings once and then goes to a busy signal.  We have tried to call Air France inn Paris but the numbers do not connect.  We have called AF in the US but they are not open for some hours yet.  Please advise what we should do, we want to fly together on one flight or the other.