This is a bit complicated.

I booked a flight on UA, connection on ANA. The outbound return on ANA had a mechanical problem making us miss our UA connection. Rebooked on AA. The agent we spoke to said she had spoken to her supervisor and that ANA would give us mileage credit on our UA accounts for the UA flights we misconnected on. It's about 7000 miles. I'm particularly concerned about losing the elite qualifying miles.

What is the best way to go about requesting this credit? I'm in the US.

(I was quite put out as ANA cancelled our connection on UA. The UA flight was delayed and we could have reached our UA connection before the doors were closed. But UA had given away our seats because ANA had cancelled us and rebooked on AA. The agents refused to rebook us on any *A flight.)

Thanks for the help.