Yes, after the ticket was issued, it was Aeroplan who told the agent that she needs to collect another 15,000 miles.
As noted, I don't want the AC ticket agent to get in trouble.
I have great sympathy for the agent in this situation (and in most) but if the agent issued a ticket and gave incorrect assurances to a customer, perhaps getting into trouble (not fired, but a reminder) is appropriate. In any case, since the error is known by (AC|AP), the agent's not likely to get into more trouble for doing the wrong thing and the customer refusing to correct it, than for doing the wrong thing and the customer agreeing. I say all this on the assumption that it wasn't the agent who discovered the error but AC|AP.
=aw
[Emphasis added.]