I'm not sure if the BC discs install the main game? I remember when I reinstalled I used a demo disc from 03 or 04? It was a trial DVD, and it installed the client which downloaded the mass amounts of updates (takes ALL DAY KTHX) because of the early version of the trial dvd. then I did e-activation for BC which 'unlocked' that portion of my gameplay, and for Wrath I actually used install discs which knocked me back to a few HUEG patches earlier, and had to repatch to 3.2.0
I think in this case you may want to uninstall, download the universal client off their website, install that, then BC and wrath.