Cancel Upgrade - Cant get through to call centre

Prelene processed a change in my contract. I have been trying to cancel this but I am either on hold for a very long time or I get transferred to different departments and get no-where.<br> <br> I have now received the Smart tab and this needs to be collected asap.<br> <br> I wish to cancel the change and would like to return to how my contract was structured before this change. Please urgently contact me<br>