Disgusting Service

An agent called to inform me that I was due for an upgrade. I agreed to upgrade and she offered me the choice of two colours which she confirmed was in stock. I chose the blue colour which she repeated to me about three times to confirm my choice of colour. When I received the confirmation of upgrade on e-mail, the letter stated that the device was black and not blue like I had chosen. At no time did the agent inform me that there is no guarantee of the colour chosen. I then called the call centre and the agent advised me that she can reverse the upgrade and then re-do the upgrade but this will take another 6 working days for the reversal to be effective. I agreed to this. during this time, I received an sms saying that my device is going to be delivered. I was rather surprised as I thought that this was in the process of being cancelled. I then called the call centre again, spoke to two agents and then asked to speak to the manager. The agent advised that the manager was on another call and would call me back. Two hours later, the courier came with the delivery but I didn't accept delivery and asked them to cancel the delivery. After the courier had left, I called back again requesting to speak to the manager and was told that he will contact me as soon as he gets a chance. I did not receive a call that day. I called again today to speak to the manager and was told that they will get back to me. I am really digusted and angered at the really bad service and a simple request to cancel the upgrade as I was not happy with the colour choice. How many calls more do I need to make before this gets resolved!!!