No, I don't have to suggest alternatives
absolutely, quite right. You’re not obliged to provide solutions to anything. However;
If your MP doesn't respond to you in a way that you like then you need to find a way to complain that doesn't make you look like you are a seven year old.
if you don’t have an alternative suggestion to problems people have encountered then it makes your personal feelings on others actions impotent and largely irrelevant. You just become a voice offering nothing but demanding the mythical ‘something’.