No, we can't undo this.
We support the mIRC client, we don't have anything to do with what happens on IRC networks or channels. It would be like calling up Microsoft support to ask why Facebook deleted your account.
The only people responsible for that ban are the ops in #cod4.wars, you will have to speak to them and them ONLY. First, you should ask WHY you were banned. The reason might be unknown to you, but that does not mean it wasn't legitimate. They might (and probably) have a very good reason.