Boarding Times
BobBHX
Passengers are called to the gate to get them ready for the anticipated boarding time. There are times when this can't be met and you have to wait a little longer. Various reasons include cabin crew dragging their feet with their checks, extra cleaning due to the mess left by inbound passengers, airline rules not permitting boarding and fuelling, technical problems occurring at the last minute, the list goes on and on. These can not be factored in so you need to call the flight so that you are ready on time.
In your case I would guess that due to holding the aircraft required either fuelling, or more fuel than anticipated. LH do not permit boarding and fuelling, so until it is finished you have to sit and wait.
As for updating you, what did you want to hear? UA could tell their passengers the a/c was in PIK and would be able to give about an hours notice of it arriving. Your a/c would probably have been over BHX going round in circles with acars keeping LH updated so their system would have rolling updates for your smart phone app. Apart from an airport radar screen and FR24 on the internet the people on the ground wouldn't have a clue what was happening as many crews seem to be allergic to calling up and giving updates, no matter how good or bad the groundstaff are they are not psychic and can't give updates they don't have. Add on non stop phone calls asking for updates from other departments and airlines and you will appreciate the conditions the staff have to work in.