Unable to use new upgrade phone

On the 1st of June I called the upgrade line to query what would happen if I upgraded to a phone with a nano sim as my current phone has a micro sim. I was advised that I would receive a new sim and when I put it in the new phone it would activate and my current one would automatically be deactivated. I was happy with this, so went ahead with the upgrade, received the phone the following day and inserted the sim card. By the 3rd it had not been activated so I contacted the upgrade line again to enquire. I was then told that my new contract would only activate on the 31st of June. To which I advised that it wasn't the benefits from the contract I was wanting, it was the activation of the sim card. I was asked to leave my name and number so that the agent I had originally dealt with could phone me back. To date I have not received a phone call, my sim has obviously not been activated and I sit with a new phone that I cannot even use. I would appreciate someone contacting me and sorting this out, as what would be the point of me ordering a new phone which I cannot make use of???? Thank you.