I am going to be harsh when I say this. I don't care if your 'friend' or some other significant person told you it was okay.
While you are on a server you will follow the rules or face the consquences.
You should already know that griefing isn't allowed due to three bans on it.
THERE IS NOTHING THAT JUSTIFIES GRIEFING.
I am not convinced that if I let you back on you wouldn't just grief again.