Exciting delays and queues enroute, wherein automated systems falsely block our progress

 Qatar: [20mar22] wake-up at 4:30 (Margo & Charles had arrived home at 1am from their trip); Margo woke up to say goodbye and thanks.  

Uber 5am to Doha airport, check-in, long queue at lounge, then long queue at gate A5, onto QR3 to Heathrow, seats 60f&g, movies Get Out, Military Wives, The Accountant, The General, Cat on a Hot Tin Roof.

    Plane lands at 12:30 local time at Heathrow, but waits for 30 minutes for a gate to open (this A380 requires special jetway); we are in row 60, so it takes a while for us to deplane, get the underground train back to the main terminal and enter the automated boarding-pass checker, which refuses: Go To Reservations Desk.  Over a hundred people are crowded around the nearby Customer Service desk, and our individual queries to several official persons nearby confirm that we must stand in the Very Long Queue to get our problem addressed – evidently because our attempt to enter the boarding area was after the cutoff time for that flight's departure schedule.  

    This was particularly ironic, as my first attempt (while standing in the queue) to telephone British Airways customer support had resulted in the guy telling me he could not do anything because our next flight was delayed, had not yet departed.  It departed 30 minutes late, though the official display board was never updated until that actual time, so it is unlikely that the computer would ever have let us board (as the computer only knew the original schedule, until the actual departure).  

    More waiting, and several cut-off phone call tries to BA;  at 4pm, a knowledgeable phone agent recommends that I exit the sterile area and walk to the Qatar Airways ticket counter.  As I feared leaving the crowded secure area, we waited in the queue for BA customer service person, fifteen more minutes:  "sure, I can book you on the next flight tomorrow morning; but in order to get a hotel & meal voucher you must go to Qatar Airways ticket counter."  

    So we exit the secure area, wend our way to the departures area and the QA ticket counter, where they direct us to the small side desk with a harried but patient Qatari manager assisting several other desperate passengers.  Twenty minutes later, he patiently hears our story, then makes some phone calls (evidently to the hotel), and writes out a hotel, dinner, and breakfast coupons for us.  It's now 6pm, and we hike through the underground tunnels to the Sofitel, get dinner, and sleep.