Chapel Hill Guy, Let me go through what I am sure from experience. Once *A award has been ticketed, but not yet flown, UA has changed dates without any fees and issues new paper tickets.

My advice was how to secure a trip using miles, thus being able to book hotels and make plans. Securing with RG (that releases seats way in advance) and eventually swapping afterwards for a carrier of choice (that has a different way of allocating award seats). Is there a fee when changing *A carriers ? Don't know, not sure. Cost in miles is the same.

Technically there might be a fee as the description of the award might be slightly different, from a *A award to an all UA award. If you keep the mix of *A carriers, then the description is even the same. Even so, I've had awards pulled out, for the correct number of miles, and wrong descriptions. I didn't complain as the math at the end of day was 100% correct.

Have you tried thanking for the assistance, and... calling again ?