Process is as follows:
1) Order the new service
2) Request from support data migration from old to new
For data migration to happen usernames must match and you must have both service active for a period of time, preferrably 3+ days. On large accounts (say 50TB+) reserve week or more depending on your server load.
Data migration can take quite a bit of time, on small account you must reserve couple days for that to happen and to verify it.
