I am also having major problems trying to get my 4 alt-accounts set up.

After nearly 4 days of effort, I'm now at the following point:

Account1: (my main account, since beta, all good to go)
Account 2: Fully active, good to go.
Account 3: Fully active, good to go.
Account 4: Opened as trial, upgraded to WowClassic, upgraded to BC, but trial restrictions still not lifted.
Account 5: Cannot create. Just flat out can't. Error 203, please contact Blizzard Billing who by the way still have not responded after 3 days.