If one of the top 10 coa shooted  a small coa.... maybe there's a reason .... pan raiding or capital raiding or i don't know...

If there are really no reason then raid them and their pan during each pvp...

play and act as a coa so a team with goal....   built lights & heavies, hundreds of lights  per people maybe 1 or 2 thousand per people per two weeks (easy to do), some hundreds of heavies  and send them on their pan during each pvp with coa multiplicator.... you're going to improve your ranking with some coalitions achievments and win some phalang. And then this coa is going to have a good reason to raid you..... lol.... but maybe they will prefer diplomacy..... 

but first check if they raided your coa without any reason... ask them, use some diplomacy ;-)

have good game. It's a war game... even a low rank coa can bother a higher lvl one's... ;-)

Have fun