Esto es lo que me ha respondido Amazon Uk a mi pregunta de porque a mi me lo han enviado por Deustche Post DHL, por si a alguien le sirve
Dear Customer,
Thank you for contacting Amazon.co.uk.
First, please accept our sincere apologies for any inconvenience this issue may have caused to you. We highly appreciate your patience and understanding in this case.
Further to your email, I would like to inform you that as our ordering system assigns a carrier to your order automatically at the time of dispatch. Unfortunately this order was not dispatched via courier as you like. Since this is automatic process we are unable to instruct the ordering to system to select the carrier as per customers choice. Please accept my apology in this regard.
I'm sorry that you disapprove of this feature; however, this is how the ordering system works at the moment. There are possibilities that these features may be changed in future. Rest assured that I have brought this to the attention of the appropriate department within Amazon.co.uk for consideration.
The estimated delivery date given for this order #XXX-XXXXXXX-XXXXXXX is December 31, 2010.