Originally Posted by
Phl06
When you have them combine over the phone and apply the voucher if the UA ticket is more expensive than the *A ticket then does the refund come back in the form of a new voucher?
It depends upon the specific fare rules, because this has to be processed as a change, not a refund and rebook. So, if the fare rules say that there will be no residual credit given if the new fare is lower, you'd be SOL. (Yes, there are a few fares that say that).
I agree with the advice to find a flight where the price is as close to the one you want as possible and go from there.