BOS-DCA-DTW (Detroit) and then DTW-PHL-BOS. Unfortunately, DTW-PHL flight was delayed and husband missed the final leg. He instead rented a car and drove home - and USAir promises to refund that portion of the trip since they were unable to get him to BOS that day.

How are they going to compute the refund amount?

I am afraid it won't matter how; they will come up with an amount and you won't have much say about it. If questioned, they will have some odd formulary that they say they used and it will be TIOLI. Take it or leave it.

I assume you looked at the receipt.

you'll get that portion of the taxes back but i don't know how they computer a portion of the fare.

MrW - the "receipt" indicates total fare for the total RT itinerary - I was wondering how they compute cost of 1 leg - especially since of the 4 legs, flights between BOS and PHL are usually the most expensive.

I was hoping that you would find that the receipt showed the fare basis and price for each leg and that there was a fare break at PHL (which would be unlikely).

Like your receipt, I have United receipts which show the fare and fee summary but not the fare construction info (which they used to show) like the following example from itasofteare:
Fare construction
BOS US CHI 159.07SA7KN US BOS 187.91VA0KN USD 346.98 END ZP BOS ORD XT 26.02US 7.60ZP 5.00AY 9.00XF BOS4.50 ORD4.50

One cannot go by the fare construction because that calculation assumes all legs are flown. What they usually will do is calculate the fare of the itinerary you actually flew and net that against what you originally paid. Sometimes they will take original ticket advance purchase into account and sometimes not.

Simple example. One way fare between AAA and BBB is, say $500. A roundtrip excursion fare could be had for, say, $400. If you buy a RT but only fly the outbound they will want to charge you the $500 for the one way (although in this case they will just call it a wash ... ie, no refund).

The reason I was asking is we need to bill the client (husband is self employed) for travel - and it is now more complicated than RT air - since it is RT air, minus refund for final leg, plus cost of car rental. Guess we will just wait until it appears back on our credit card (they promised within 2 weeks - we did this once before and that was about how long it took)

Did you get refunded?

Update - they credited our credit card $147, a seemingly random amount. Airfare PHL-BOS is about $350 one-way/$700 RT - for some reason this route is ridiculously high cost. Wondering if they have a $ per mile formula - rental car cost $160 plus gas/tolls. It is all getting charged to client anyway.