Ok, so say we boycott porn, we also boycott Mars - should be just as easy an ask ...who/what else should we boycott? Where does boycotting any and every company that deals in exploitation lead to? What are the implications for those who work in these businesses who are not being exploited? Or should there be tighter regulation - some of the suggestions made by frosted above?
It leads to greater income and financial stability competing brands that don't use slaves, is where it leads. Brands who do use slave labour, will, given enough incentive, make the effort to change their labour model and gain fair-trade accreditation.
It doesn't matter how many times you keep finding new ways to say that you think bothering about it is pointless, I'm not going to agree.
So, buy an up-to-date copy of the Good Shopping Guide and make brand decisions based on that. This is a sample page of the washing up brand comparison table from an old copy.