Yes you are understanding perfectly, which is much more than I can credit the TM rep with. When I asked her to tell me what the message was that she was going to be relaying to the promoter on my behalf (har har!) she began "you went to a different website..." Um, NO.
I think you are right about the cc avenue--I'm going to tell Visa I refute the charges due to the fact that I did not buy tickets for St Louis, so this is not quite bait-and-switch but comes down to a glitch in their system that they are going to pawn off on fans.
btw I tried the Phoenix presale email from U2.com again