Can't update the client

[Graani]

Hello!
I wanted to update my 3.3.5a client to 4.0.6a to try new things, so I first downloaded 3.3.x to 4.0.0 patch. However, when I unpacked it, there were four files inside:

WoW-3.3.0.10958-4.0.0.12911-NA-Stage-1
WoW-3.3.0.10958-4.0.0.12911-NA-Stage-2
WoW-3.3.0.10958-4.0.0.12911-NA-Stage-3
WoW-x.x.x.x-4.0.0.12911-Updater.exe

Now, I can't seem to be able to update WoW with that. I try to launch the exe file and all I get is "Blizzard updater was unable to start up. There is no patch file to apply.". The same happens if I copy the files to client folder.

I'm not really sure what to do. I know it's different in later versions, but with my current 3.3.5a I have no files like "patch.mpq" or "Updates" folder. I don't know how to update it, and I didn't find any useful tips on the Internet either. Normally, there was no trouble with applying the patches with attached exe files.
By the way, sorry if the topic is in the wrong place. I didn't find anything better.

Thanks for help.

PS: I've tried putting these files in (created myself) "Updates" folder as well. Running the exe still doesn't work, and launching Blizzard Downloader gives the message that "Data for the next patch is not available". I don't know if it's important, but this message pops out after a while. At first, when I launch the Downloader, it looks like nothing happened. After a minute or two, the message pops out.