Perhaps there was another direct flight?
Do you think LHR is an solution/upgrade?
Hang on to that happy thought when you go through the s*** show that is is LHR terminal 3 to terminal 5:
1. Line up for bus to #5, after traipsing all over hell and beyond with hundreds of people from other flights.
2. Get on an over packed transit bus with minimal seating, but LOTS of standing, from #3 to #5. It won't take long, but will seem like forever.
3. Re-clear customs with no status recognition (No PreCheck/No Premium class lines)
4. Clear security (anything more would be vitriol)
5. Get on plane
6. Have a nice flight.