Do you have "wow-update-enGB-18273.MPQ" file in WoW/Data/enGB folder? If not, then copy/paste it in from the .7z archive (Data/enGB/wow-update-enGB-18273.MPQ from the archive).
Also, make sure you have these files under WoW/Data folder:
If you don't have them, then copy them in your WoW/Data folder from the .7z archive (.MPQ files under Data/ in the archive).
Lastly, make sure you copied and replaced WoW.exe from the .7z archive (take WoW.exe from the .7z archive and put it in your WoW/ folder, replacing existing one).
If you still have problems, then you should post screenshots of WoW/, WoW/Data and WoW/Data/enGB folder contents, so I can find out what is exactly missing from your client.
Also, make sure you have these files under WoW/Data folder:
- wow-update-base-18273.MPQ
- wow-update-base-18548.MPQ
- wow-update-base-18549.MPQ
If you don't have them, then copy them in your WoW/Data folder from the .7z archive (.MPQ files under Data/ in the archive).
Lastly, make sure you copied and replaced WoW.exe from the .7z archive (take WoW.exe from the .7z archive and put it in your WoW/ folder, replacing existing one).
If you still have problems, then you should post screenshots of WoW/, WoW/Data and WoW/Data/enGB folder contents, so I can find out what is exactly missing from your client.