when you spoke to customer services they will have confirmed if the order had not closed down correctly. Unfortunalty BT's system only allows one order at a time, so they will then have to raise this with the mobile/connection team to get them to manually close the order.
Once that order has been closed, the system will allow you to order another mobile on the same account. Once an order has been placed and accepted customers normally get the new handset the next working day.
Unfortunatly the agent will not know when the connection team will resolve the issue so they will have given you a time frame.
If the issue has not been resolved by tomorrow and you need another handset you could try and create a second BT account, order a new handset and when the issue has been resolved ask to have the new account merged with the old one..