I solved this problem by deleting the Black Swan app . . .
(see below for instructions on how to delete the app)
. . . and then I redownloaded the app from scratch, starting from the link sent in my email,
http://voicecentral.riverturn.com/install/I was prompted for my user login and password, restarted into the premium version, and then let the contacts list sync without interruption. The pictures were all there, as expected and paid for.
To delete the app, do this.
# From the main screen on the iPhone or iPod touch, find and hold the VoiceCentral icon until the screen starts to wiggle and the X sign appears.
# Tap on the X sign and when prompted to Delete VoiceCentral, select Delete.
# Press the home button to return to the home screen.
# Launch the Settings app.
# Select Safari.
# Go to Databases.
# Tap the Edit button.
# Delete the VoiceCentral database by pressing the red icon.
# Hit Done.