I don't like Windows servers myself... but it seems more like your provider is unreliable nowadays. I am sure there are hosts, who have virtually no problems running and maintaining a Windows Server.
If I were you, I would make backups of your data and databases now. If they let there mail server go this long without fixing...think if the http server was down. Or what about FTP (and then you wouldn't be able to download your backups)?
Perhaps it's time to find a new host... There is plenty of Linux hosts who would be more than happy to give you decent service.
I am concerned to note that Windows servers are becoming totally unreliable nowadays.
The same can be said for any OS, when in the wrong hands. The problem is with your provider, not the Windows OS.
If you're unsatisified with your provider than the right thing to do is move. Don't let their inadequacies desuade you from going with another Windows service provider, however. The Windows server OS has all the tools and options available to make it incredibly stable and secure. Some providers simply don't know how to manage a server.