Try the bono card. http://en.granadatur.com/granada-card However, it looks like it may be sold out for the Alhambra on those days.
Also check viatour to see if they offer a guided tour on your dates
Also, there are slots for same day tickets. I'd research this, but if it opens at 8...get there at 6 and get in line. Preferably one person in each line - the line for the credit card machine and the line for the manned ticket desk. Whoever is in the faster line buys the tickets.
Finally, there may be tickets available for the gardens and fort - not the palace. Even if you can't get palace tickets, get the garden one and go up there. Heck, even without tickets you can wander around a bit (Charles V, museums in that area, views, the baths...) and go to the parador. Even that is worth it if nothing else is available