Q: can't accses xls file on iPad 3

Get dropbox.  Can you view the excel file now?  What xls viewing app are you using?

Look at the Rccharles answer on this post.

https://discussions.apple.com/thread/6033082?tstart=0

Also, you can download these free MS Office apps (Word, Excel, PowerPoint) to view (but not create or edit) these files.

https://itunes.apple.com/us/app/microsoft-word-for-ipad/id586447913?mt=8

https://itunes.apple.com/us/app/microsoft-excel-for-ipad/id586683407?mt=8

https://itunes.apple.com/us/app/microsoft-powerpoint-for-ipad/id586449534?mt=8

Microsoft Office for iPad:Early Reviews of Word, PowerPoint & Excel Apps

http://ipadacademy.com/2014/03/microsoft-office-for-ipad-early-reviews-of-the-wo rd-powerpoint-excel-apps

How to get all the iWork apps, iPhoto, and iMovie for free on an eligible iPhone or iPad

http://www.imore.com/how-get-all-iwork-apps-iphoto-and-imovie-free-eligible-ipho ne-or-ipad

About Free Apple Apps for iOS 7 compatible devices

http://support.apple.com/kb/HT5913

 Cheers, Tom