Tried searching to see if anyone has run into this before but the search results were not exactly on target...anyway

I have a trip coming up next week that was a group ticket purchased through a TA. There are 22 people on the PNR including myself. Until I called UA last night it wasn't even showing in my MP account but that was rectified with a phone call. Looking at the reservation now, I see my seat assignments but it won't let me change them. I get a "You cannot select a seat for this type of reservation." Message. The current seat selections are all AWFUL (over row 30 on A320/738) and not even "preferred" let alone E+

I don't believe this to be basic economy based on:
A) Already having a seat assignment (even if it is crappy)
B) The fare buckets we are booked in (W and U)
C) The earnings for this trip don't reflect basic economy

Ideally I'd like to buy an F upgrade but even without that I'd like to choose a less awful seat. Is this possible?