I'm of the opinion that in the first instance the supplier should be given a fair chance to rectify the situation.
If the supplier fails to offer a solution, within a reasonable time then it's fair for it to be posted on a forum such as this.
So long as the information presented is factual, I can't see that there's a problem.
RCS is right, in my opinion. Either ban ALL posts about problems with suppliers or ban none of them.