I back up my website myself onto my hard drive on a regular basis. It only takes moments. I use Carnonite (http://www.carbonite.com) as my backup service. Carbonite automatically updates your files on their server so you don't have to remeber to do it.
I own to my hard drive to regularly back up my website. Only an instant. I use my backup service Carnonite. Worry-free automatic update your own files on the server, so you do not have to remember to do so.It is very famous & secure site for the data backup.
Not sure if you are aware of "StoreGrid", a backup software which can perform offsite backups added with plenty of useful features. You can check if one of its various editions (including an edition for webhosting providers) meets your requirement.