They should not, but they can, but do you really think they will do it?
Let's see:
- They have the admin rights to update, change, maintain... all their machines where you are putting your data.
So they can do it.
- You should get a legal agreement with some data protection specifications that would fit your needs.
I guess that the only way you would have to secure your data is using your own server.
Hope this helps...
Take a look at this link...
http://lifehacker.com/124212/geek-to-live--how-to-set-up-a-personal-home-web-server[
^]
It would be cheaper if you would do it using a free Linux distribution with all the packages preinstalled... take a look at fedora, ubuntu... This won't be a matter of 5 minutes, but a small thing can be done in less than nothing... anyway, then you will have to maintain it... but... it is up to you to decide if it is the way to go or not...