Customer Pay for Soy Sauce to Dip Sushi

We've eaten there a few times, enjoyed the food albeit expensive for locals. But now we've decided it is enough. We often order their sushi and ask for the low sodium, no alcohol green top bottle and each time they've made us pay for the whole bottle to take away. They do not serve it at the table, as they would only serve up the red top bottle, which of course is stranger than fiction, considering that both bottles are often served at restaurants offering sushi. We have never been made to pay for soy sauce at any other restaurant. But then Willoughby's have an arrogance about them and we will definitely not be going back there, just on principle.