You communicate to management that you are unhappy with the business practices by not giving them revenue.

They can't quantify what business practice is causing customers to leave though. They can really only quantify who comes to the store. In the US, most stores put a URL for a feedback form on their receipts. I've used these a few times to air out my grievances. I like to think it works - the bike rack and the additional self-checkout registers only came after I called the CEO a lazy loser nepo baby a few times in the feedback forms.

There are far more egregious things to guilt trip shareholders meetings over if you are going for that.