Well, but as a consumer, you have options, and your number one way to make your voice heard is to switch to a better option. (The number two way is to threaten loudly, I think.)
You have to do the latter. If you just switch without making any noise, then the company just sees you as percentage of users using the competitor's product. Not very meaningful.
You have to write a short letter saying why you once used <product> or refused to purchase <product> because of <reason>.
