Best site to book Last Supper viewing tickets

This is the official site: http://www.vivaticket.it/?nvpg[home]&op=cenacoloVinciano&change_language=1.

Hello,
I went thought the official museum website here http://www.vivaticket.it/index.php?nvpg%5Bevento%5D&id_evento=298097&change_language=1&Language=ENG&wms_op=cenacoloVinciano&SiteVersion=1
I am assuming you want the English tour so make sure you book for the allotted time slots for English tours which are 930 am and 330 pm. As of now, they are taking reservations through March 2015. If tickets are sold out for your dates, assuming the date is available for purchase, you can try a 3rd party vendor.

If your dates are not available, you can either book a tour that includes Leonardo's Last Supper and see some of Milano, or go to a vendor that sells the Last Supper tickets alone. Prepare to pay at least double the official price for the single ticket, but it's still much cheaper than the tour cost.

If the web site says they are full booked it is probably not correct. CALL 011-39-02- 9280-0360, Extension 2. I did this last year and was able to get tickets. This subject has been discussed many times on this forum and multiple replies indicated the same results. You will most likely have to call at least 4 to 6 times before you get through (It took me 4 tries). Note, this advice is in Rick Steves Italy Guide Book.

The "tours" that include the Last Supper are nothing but scams/rip-offs. What you can get for 8 euros online or by phone they charge you 60 euros.