Had a WSG two days ago which lasted like more than 30mins.
Because of the wall climbing trick on alliance side.
Some how we manage to capture the flag twice by tricking him to jump down from the wall.
But after that he got smart and not fall for it anymore.
And they can't capture their flag back, which i really don't know why.
no one stay back at their base to help defence since they can bloody climb the wall.
i assume the rest of the alliance was at our base trying to get back their flag.
Finally we decided to give up because it taking too long and simply not worth it.

So i was wonder is it allowed? Or can we complain to GM about this?
This can be done only by alliance side ? because I have not seen horde side doing it.

IIRC, it can be reported. Both sides can do it. Typical if you get Q_Q remarks but yeah, just report it and get official response.

Many people did it before, but normally after reporting it might scare them to a certain extent.

Most cases people report by posting it in wow's public forum and then have the screenshot attached. However, due to the naming and shaming policy blizzard adopt, you will just have to post about it and only post the pics after people ask for it.

We did report with screen shot but nothing happen, no respond from GM so decided to try and play see how.
But finally decided to give up after some time.

Know what is the panalty for the person that get caugth?
3 days ban?

Its a bannable offence, my guildmate (ROFL TUNN) got banned for it once. Just take a screen and make a ticket. But WoW GMs can be really meh, some are super helpful, some are stupid jerks who don't know a thing about the game they're supposedly masters of.

this also happened to me,
dumb gnome rogue loser ally
we were already 2-0 then lost 2-3 coz of this stupid ally gnome rogue wall climbing