Unauthorised Information mid-bidding
The bidding goes:
North / East / South / West
Pass / - / 2D* / - 2D announced as weak, but their partner winces when done so
3D / - / 5D / -...
North has a hand where 3D is sensible if they play strong 2's but only Pass or 4D if they play weak 2's.
South underbid their hand to start with, so is always going to 5D if their partner doesn't pass.
How would you deal with this as an UI complaint?
I'm struggling because there's an argument that no harm was done and an argument that the UI got them to game.
Obviously there's no convention card. That would be too easy. Slapped wrists whatever for the UI and declarer failing to correct the MI.