When I got to London I found that the UA flight I was rebooked on was substantially delayed (~4 hours), at which point UA rebooked me on BA. Would that qualify for mileage credit, or given that the flight wasn't cancelled (as far as I know) am I out of luck?
If UA rebooked you, you should get credit for the trip, including bonus miles. Call MP and explain the situation. Give them the ticket number and they'll look the record up. Given the delays during the summer I'd be very surprised if they didn't give you the mileage credit.
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danville 1K