Downgrading the patches in WoW

[InfeeecteD]

If i downgrade a patch in WoW (delete patch.mpq and so on), do i have to download the other patches ?
The main problem here is that i'm paying per mb-s , that is 1gb = 15 euros (and i really dnt wanna gief that money) .. Answer me plzzzzzz
Thank you!

[TRiGGS]

Check your wow install folder, chances are high that you can find the required updates in there

[SERAG N1]

dude,once you delete the "patch.mpq" file,use the repair (it's icon is displayed on triggs's reply) and select "reset and check files",and once it finishes repairing,you will find out that you have an old patch now,I remember it was 2.0.0 and you continue to patch 2.4.2