Raddy1 writes:
>after I send a claim from London to Tuscon, AZ!

Huh? UK based UA flyers should be sending such claims to the Mileage Plus desk at United's Clontarf, Dublin, Ireland offices instead of Tuscon AZ. The address you need is:
United Airlines
Mileage Plus Dept
Block T
Eastpoint Business Park
Clontarf
Dublin 3
Republic of Ireland

You'll need to send readable photocopies of the ticket backpage, the boarding passes and
a covering letter explaining the situation. I've never had a missing United credit, but I've had two from Star Alliance (one Austrian, one Air New Zealand) and in the Air New Zealand case I'd been re-routed on Virgin for the flight (because of a late arrival on an inbound Shuttle by United flight). I still got the points for the Air New Zealand leg although the credit took about six weeks to be added. No idea about special offers that would have been qualified for if you'd got the original flight though.

It takes a LOT of pursuasion and talking to a supervisor or two to make an award booking when you don't yet have enough points. I managed to get it once, but the circumstances were rather special as the miles needed had already been flown, just not entered into the computer yet. Checking the manifests for the flight, they were able to confirm that the points were "already earned" and so they let it pass - but that was VERY hard work.

Regards, Bevis.