If you can reasonably ascertain that the meat stamped as halal are halal, then you can definitely eat them; but if you are not sure, then you must not rush to make a judgement about it either positively or negatively until you have ascertained the truth about it.
Islam teaches us to be just and fair in making judgments of things and people: Allah says, “O you who believe! Be steadfast witnesses for Allah in equity; and let not you hatred of any people make you swerve from justice. Deal justly; that is closer to God-consciousness; be conscious of Allah. Allah is Aware of what you do.” (Qur’an: 5: 8).
Moreover, if a certain store is using label of halal falsely, then you can report them to the authorities; rather, I insist, that you must do so if you are honest and truly convinced of the soundness of your assessment; for that is the proper Islamic way to deal with this matter rather than rushing to make judgments and spreading rumours.
Allah says in Surat al-hujurat, “O you who believe! If a person of questionable integrity brings you some news, inquire into it carefully lest you should harm others unwittingly and afterwards be sorry for what you did.” (Qur’an: 49: 6). The Prophet, peace be upon him, warned us against indulging in gossip when he said, “Allah hates for you three things: Excessive questioning (in matters of religion), squandering wealth, and indulging in gossip!”
Finally, it is also highly important for us to know that halal remains halal no matter who certifies it, and haram remains haram no matter who certifies it otherwise. In other words, so long as a Muslim says that he has certified it as halal we are not to question him unless we have clear evidence to the contrary; we are to think good of all people, for everyone shall be deemed innocent until proven guilty.
May Allah help us all to remain steadfast witnesses of truth and justice; and may He guard us all against the perils of our tongue-aameen.