Posted: 22/05/2016 at 20:35
In my experience, saying something like, "I wonder if you can help me? I think this may be wrong . . . " brings more assistance than if it seems a bit more confrontational. It may turn out that I was wrong, or that the staff had somehow got it wrong - but it gets sorted in double-quick time.
Another opening is to say "I find it hard to complain about something, but I am concerned that . . . " and lo and behold, you have got the staff on your side from the outset.
If neither of the above works, then it's more than justified to insist on proper attention, asking for the manager if needs be.
You attract more flies with honey than with vinegar, so I heard once. (though why you would want to attract flies goodness only knows!!!)