Bill Gillette can work wonders on triggers, but you have to ask yourself if its worth the trouble sending it to the US.
Really as far target shooting goes in shotguns, you don't want a really light trigger.
Nor should you really be drawing up the slack out of the trigger, I know it's tempting and it's especially hard habit to break for pistol and rifle shooters.
But you should slap the trigger on a shotgun, not pull it in incrementally, this leads to measuring the target and also firing prematurely.
It's best to keep your finger either off or just lightly rested on the trigger, slap it quickly when the target looks right.
Jason Spencer in nepean could likely help you out, but I don't think its worth it.