You will need to go to the main ticket office in the Alhambra with the following documents:

- Photocopy of your passport/identity card
- Written authorisation from the person whose credit card was used - indicating cardholder's name, ID/passport number, last 5 digits of the credit card; the name and ID/passport number of the person authorised to collect the tickets; and the reference number allocated when the tickets were reserved.

Remember to give yourself plenty of time for this as it may take time depending on the length of the queues and it will then take you about one hour to get from the main ticket office to the Nazrid Palaces.
There are generally two queues at the ticket office: one to buy tickets and a shorter one for advanced ticket sales. So make sure you don't waste your time by queueing in the wrong queue.